I looked at all Py_3_12 changes in pyo3-ffi/src/cpython and ported them
back. Functions, structs, and fields in the code object not already
defined in python3-sys are ignored. For PyUnicode_READY, I kept a dummy
version so the cpython crate does not need change.

    Symbols missing in /opt/hostedtoolcache/Python/3.12.4/x64/lib/libpython3.12.so:
    PyCode_New
    PyCode_NewWithPosOnlyArgs
    PyUnicode_AsUnicode
    PyUnicode_AsUnicodeAndSize
    PyUnicode_FromUnicode
    _Py_GetAllocatedBlocks
    _Py_PackageContext

Python 3.12/3.11 renamed/deprecated some APIs. Update code to skip them.
This affects `linux (ubuntu-latest, 3.12, nightly)` CI.

Drop Python 2.7, as it is no longer available:

    Warning: The support for python 2.7 will be removed on June 19. Related issue: actions/setup-python#672
    Version 2.7 was not found in the local cache
    Error: The version '2.7' with architecture 'x64' was not found for Ubuntu 22.04.
    The list of all available versions can be found here: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json

Add Python 3.12 as its support was just added.

Fork macOS steps from Linux due to the ARM arch change:

- Rust 1.41 does not have a `aarch64-apple-darwin` version. The first Rust
  version that supports `aarch64-apple-darwin` is 1.49.0.
- Python 3.7 to 3.10 do not have a macOS ARM version in CI.
- Rust < 1.54 will fail on CI. See also See rust-lang/rust#107252:

    error: linking with `cc` failed: exit status: 1
    |
    = note: "cc" "-arch" "arm64" "-L" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.0.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.1.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.10.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.11.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.12.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.13.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.14.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.15.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.2.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.3.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.4.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.5.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.6.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.7.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.8.rcgu.o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.build_script_build.f402nxks-cgu.9.rcgu.o" "-o" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/build/memchr-30eba211f26bbb03/build_script_build-30eba211f26bbb03.1dr67yq0qjg3o93v.rcgu.o" "-Wl,-dead_strip" "-nodefaultlibs" "-L" "/Users/runner/work/rust-cpython/rust-cpython/target/debug/deps" "-L" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libstd-dd5aba3397285ad0.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libpanic_unwind-cb187f1a5b379d1a.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libobject-d263574460ac0b7b.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libaddr2line-0a9a23101265d9a7.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libgimli-e6457880b831342b.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libstd_detect-9590d4ced205b108.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/librustc_demangle-a1f4d95a4a2cc2a3.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libhashbrown-dbf1072a4ef077a4.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/librustc_std_workspace_alloc-7ff002204e919c46.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libunwind-a2049ddc023c32b9.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libcfg_if-02cf13a7707ef825.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/liblibc-e628929d2a4d215f.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/liballoc-1f245a76196b996b.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/librustc_std_workspace_core-49a44db0ac13b7f4.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libcore-a04810d031c48fa4.rlib" "/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libcompiler_builtins-7cd54448073dfb2c.rlib" "-lSystem" "-lresolv" "-lc" "-lm" "-liconv"
    = note: ld: multiple errors: archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libstd-dd5aba3397285ad0.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libpanic_unwind-cb187f1a5b379d1a.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libobject-d263574460ac0b7b.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libaddr2line-0a9a23101265d9a7.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libgimli-e6457880b831342b.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libstd_detect-9590d4ced205b108.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/librustc_demangle-a1f4d95a4a2cc2a3.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libhashbrown-dbf1072a4ef077a4.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/librustc_std_workspace_alloc-7ff002204e919c46.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libunwind-a2049ddc023c32b9.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libcfg_if-02cf13a7707ef825.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/liblibc-e628929d2a4d215f.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/liballoc-1f245a76196b996b.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/librustc_std_workspace_core-49a44db0ac13b7f4.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libcore-a04810d031c48fa4.rlib'; archive member 'lib.rmeta' not a mach-o file in '/Users/runner/.rustup/toolchains/1.53.0-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/lib/libcompiler_builtins-7cd54448073dfb2c.rlib'
            clang: error: linker command failed with exit code 1 (use -v to see invocation)