Update macOS 12 to macOS 13 in CI #3138

Job	Run time
Check MSRV	46s
Lint macOS x86_64	2m 23s
Check formatting	11s
Lint iOS ARMv7s	2m 18s
Lint visionOS Aarch64 simulator	2m 18s
Lint GNUStep + exceptions	1m 20s
Lint header-translator	30s
Lint test-assembly	28s
Test macOS 15 Aarch64	1m 35s
Verify header translator output	59s
Check framework features	4m 49s
Assembly tests	3m 37s
Test macOS 13 x86_64	4m 48s
Compiler UI	42s
Test macOS 15 AArch64	2m 40s
Test Compiler-RT	29s
Test GNUStep with libobjc2 v1.9	1m 57s
Test macOS 14 Aarch64 nightly	3m 7s
Test on iOS simulator w. dinghy	19m 31s
Test GNUStep with libobjc2 v2.0	2m 6s
Build macOS 13 x86 with 10.13 SDK	5m 50s
Test GNUStep with libobjc2 v2.1 on nightly	1m 30s
Test macOS 13 x86_64 with 10.12 SDK	3m 22s
Test GNUStep 32bit	1m 47s
Build iOS x86_64 simulator	1m 41s
Test Mac Catalyst Aarch64	3m 25s
Build visionOS Aarch64	3m 21s
Build tvOS Aarch64	4m 29s
Build watchOS ARM64_32	2m 57s
Build iOS ARMv7s	2m 30s
Build iOS x86	4m 2s
	1h 31m 28s

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