Use built-in `swift-testing` for Xcode 16 #234

Job	Run time
Generate matrix	2s
Danger	50s
Test(Linux) (5.10)	4m 12s
Test(macOS) (15.4, macOS)	2m 33s
Test(Linux) (5.9)	4m 11s
Test(macOS) (15.4, iOS)	14m 25s
Test(macOS) (15.4, watchOS)	5m 41s
Test(macOS) (15.4, tvOS)	5m 23s
Test(macOS) (15.2, macOS)	3m 4s
Test(macOS) (15.2, iOS)	8m 56s
Test(macOS) (15.2, watchOS)	4m 48s
Test(macOS) (15.2, tvOS)	5m 50s
Export xcodebuild test result	46s
	1h 0m 41s

Provide feedback