Update CI to Xcode 15.1 #6395

Job	Run time
changes	4s
spm-binary-cron	0s
check	3m 50s
sanitizers-mac (macos-12, asan)	4m 10s
sanitizers-mac (macos-12, tsan)	40m 52s
sanitizers-ubuntu (ubuntu-latest, asan)	2m 7s
cmake-prod-db (macos-12, (default))	8m 56s
cmake (macos-12)	6m 3s
cmake-prod-db (macos-12, test-db)	37m 51s
cmake (ubuntu-latest)	1m 49s
pod-lib-lint (FirebaseFirestoreInternal.podspec)	24m 16s
pod-lib-lint (FirebaseFirestore.podspec)	31m 20s
pod-lib-lint-cron	0s
pod-lib-lint (FirebaseFirestoreSwift.podspec)	22m 18s
spm-binary	3m 43s
spm-source (iOS, macos-12)	9m 32s
xcodebuild (iOS)	33m 15s
spm-source (iOS, macos-13)	7m 44s
xcodebuild (tvOS)	13m 49s
spm-source (tvOS, macos-12)	6m 33s
xcodebuild (macOS)	14m 48s
spm-source (tvOS, macos-13)	8m 12s
spm-source (macOS, macos-12)	6m 57s
spm-source (macOS, macos-13)	7m 53s
Check all required Firestore tests results	1s
	4h 56m 3s

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