ci: Finish migration to Github Actions #61

Job	Run time
Compatibility test	4m 59s
Integration test / Linux (5.8)	22s
Integration test / Linux (5.9)	1m 41s
Example packages / Linux (5.8)	24s
Integration test / Linux (5.10)	1m 34s
Example packages / Linux (5.9)	10m 57s
Integration test / Linux (nightly-6.0)	2m 17s
Example packages / Linux (5.10)	10m 59s
Soundness / API breakage check	2m 48s
Integration test / Linux (nightly-main)	2m 5s
Example packages / Linux (nightly-6.0)	10m 56s
Soundness / Broken symlinks check	2s
Example packages / Linux (nightly-main)	10m 55s
Soundness / Documentation check	1m 42s
Soundness / Format check	43s
Soundness / License headers check	9s
Soundness / Shell check	34s
Soundness / Unacceptable language check	3s
Swift 6 Language Mode / Swift 6 language mode	46s
Unit tests / Unit tests / Linux (5.8)	23s
Unit tests / Unit tests / Linux (5.9)	1m 30s
Unit tests / Unit tests / Linux (5.10)	1m 39s
Unit tests / Unit tests / Linux (nightly-6.0)	2m 6s
Unit tests / Unit tests / Linux (nightly-main)	2m 50s
	1h 12m 24s

Provide feedback