Set Rust edition to 2021 #28

	---
	name: Build and test
	on:
	pull_request:
	paths:
	- .github/workflows/build-and-test.yml
	- '*/.rs'
	- Cargo.toml
	- Cargo.lock
	workflow_dispatch:

	env:
	CARGO_TERM_COLOR: always
	RUSTFLAGS: --deny warnings

	jobs:
	build-and-test:
	strategy:
	matrix:
	# Keep MSRV in sync with rust-version in Cargo.toml as much as possible.
	rust: [stable, beta, nightly, 1.62.0]
	runs-on: macos-latest
	steps:
	- uses: actions/checkout@v4

	- uses: actions-rs/toolchain@16499b5e05bf2e26879000db0c1d13f7e13fa3af #v1.0.7
	with:
	toolchain: ${{ matrix.rust }}
	profile: minimal
	default: true

	- name: Build
	run: cargo build --all-targets --locked

	- name: Test
	# Since the tests modify global state (the system firewall) they cannot run in parallel.
	# The integration tests must run as root since they write firewall state (/dev/pf)
	run: sudo cargo test -- --test-threads=1

	# Make sure the library builds with all dependencies downgraded to their
	# oldest versions allowed by the semver spec. This ensures we have not
	# under-specified any dependency
	minimal-versions:
	runs-on: macos-latest
	steps:
	- uses: actions/checkout@v4

	- uses: actions-rs/toolchain@16499b5e05bf2e26879000db0c1d13f7e13fa3af #v1.0.7
	with:
	toolchain: nightly
	profile: minimal
	default: true

	- name: Downgrade dependencies to minimal versions
	run: cargo +nightly update -Z minimal-versions

	- name: Compile with minimal versions
	run: cargo build --all-targets

Provide feedback