Update to Xcode 14.3, and update rustc nightly #2117

Job	Run time
Check formatting	14s
Check MSRV	1m 52s
Lint macOS 64bit	4m 29s
Lint iOS 32bit	1m 27s
Lint GNUStep + exceptions	1m 49s
Lint header-translator	33s
Lint test-assembly	38s
Test macOS 12	6m 27s
Assembly tests	53s
Verify header translator output	1s
Compiler UI	1s
Test Compiler-RT	50s
Test GNUStep with libobjc2 v1.9	2m 35s
Test GNUStep with libobjc2 v2.0	2m 42s
Test GNUStep with libobjc2 v2.1 on nightly	2m 41s
Test GNUStep 32bit	2m 33s
${{ matrix.name }}	0s
Check icrate features	0s
Test on iOS simulator w. dinghy	0s
	29m 45s

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