ci: update actions/checkout to v4 #325

Job	Run time
carthage	1s
cocoapods	2m 18s
build (5.10, 15.4, macos-14)	49s
example (Maps)	1m 45s
build (5.9, 15.2, macos-13)	46s
swiftpm (iphoneos, arm64)	18s
swiftpm_old (x86_64-apple-ios16.4-simulator, 14.3.1, macos-13)	37s
build (5.8, 14.3.1, macos-13)	48s
swiftpm (iphonesimulator, x86_64)	19s
swiftpm_old (arm64-apple-ios16.4-simulator, 14.3.1, macos-13)	39s
build (5.7, 14.1, macos-12)	1m 10s
swiftpm (iphonesimulator, arm64)	22s
swiftpm_old (x86_64-apple-ios15.7-simulator, 14.1, macos-12)	46s
build (5.6, 13.4.1, macos-12)	52s
swiftpm_old (arm64-apple-ios15.7-simulator, 14.1, macos-12)	40s
build (5.5, 13.2.1, macos-12)	1m 50s
example (Maps-SwiftUI)	57s
test (17.5, 15.4, iPhone 15 Pro, NO, macos-14)	5m 6s
build (5.4, 12.5.1, macos-11)	1s
build (5.3, 12.4, macos-11)	1s
test (16.4, 14.3.1, iPhone 14 Pro, NO, macos-13)	5m 18s
example (Stocks)	52s
build (5.2, 11.7, macos-11)	1s
test (15.5, 13.4.1, iPhone 13 Pro, NO, macos-12)	4m 30s
example (Samples)	57s
	31m 43s

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