Update to Xcode 14.3, and update rustc nightly #2111

Job	Run time
Check MSRV	1m 35s
Lint macOS 64bit	5m 2s
Lint iOS 32bit	1m 7s
Lint GNUStep + exceptions	2m 1s
Lint header-translator	51s
Lint test-assembly	39s
Check formatting	12s
Test macOS 12	5m 24s
Verify header translator output	0s
Assembly tests	0s
${{ matrix.name }}	0s
${{ matrix.name }}	0s
Test on iOS simulator w. dinghy	0s
Check icrate features	0s
Compiler UI	0s
Test Compiler-RT	0s
	16m 51s

Provide feedback