Set buttonStyle to be MainActor #804

Job	Run time
spm-build-test (macos-latest, iphonesimulator)	1m 16s
pod-lib-lint (macos-13, GoogleSignIn.podspec)	16m 16s
pod-lib-lint (macos-13, GoogleSignIn.podspec, --use-static-frameworks)	12m 39s
spm-build-test (macos-latest, macosx)	3m 0s
pod-lib-lint (macos-13, GoogleSignInSwiftSupport.podspec)	11m 25s
pod-lib-lint (macos-13, GoogleSignInSwiftSupport.podspec, --use-static-frameworks)	9m 8s
pod-lib-lint (macos-13, GoogleSignIn.podspec, --use-static-frameworks)	18m 12s
pod-lib-lint (macos-13, GoogleSignIn.podspec)	12m 55s
pod-lib-lint (macos-13, GoogleSignInSwiftSupport.podspec)	9m 3s
spm-build-test (macos-latest, macosx)	1m 21s
pod-lib-lint (macos-13, GoogleSignInSwiftSupport.podspec, --use-static-frameworks)	18m 9s
spm-build-test (macos-latest, iphonesimulator)	1m 5s
	1h 54m 29s

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