Migrate CI to use GitHub Actions. #8

Job	Run time
Swift 6 Language Mode	0s
Unit tests / Unit tests / Linux (5.9)	2m 39s
Unit tests / Unit tests / Linux (5.10)	2m 44s
Unit tests / Unit tests / Linux (6.0)	1m 32s
Unit tests / Unit tests / Linux (nightly-6.0)	3m 9s
Unit tests / Unit tests / Linux (nightly-main)	3m 5s
Unit tests / Unit tests / Windows (6.0)	1s
Unit tests / Unit tests / Windows (nightly-6.0)	3s
Unit tests / Unit tests / Windows (nightly-main)	2s
Soundness / Format check	40s
Soundness / API breakage check	2m 7s
Soundness / Broken symlinks check	4s
Soundness / Documentation check	1m 37s
Soundness / License headers check	6s
Soundness / Shell check	34s
Soundness / Unacceptable language check	4s
Soundness / YAML lint check	6s
Soundness / Python lint check	5s
Cxx interop / Cxx interop / Linux (5.9)	1m 18s
Cxx interop / Cxx interop / Linux (5.10)	1m 17s
Cxx interop / Cxx interop / Linux (6.0)	1m 34s
Cxx interop / Cxx interop / Windows (6.0)	3s
Cxx interop / Cxx interop / Linux (nightly-6.0)	1m 44s
Cxx interop / Cxx interop / Windows (nightly-6.0)	1s
Cxx interop / Cxx interop / Linux (nightly-main)	1m 49s
Cxx interop / Cxx interop / Windows (nightly-main)	1s
	26m 25s

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