Disable warnings as errors on Swift 6 and main #138

Job	Run time
Soundness / API breakage check	2m 33s
Integration tests / 5.8	12m 55s
Cxx interop / 5.8	1m 5s
Benchmarks / 5.8	2m 41s
Integration tests / 5.9	14m 50s
Benchmarks / 5.9	3m 38s
Cxx interop / 5.9	1m 14s
Integration tests / 5.10	14m 6s
Benchmarks / 5.10	3m 32s
Cxx interop / 5.10	1m 11s
Integration tests / nightly-6.0	17m 11s
Cxx interop / nightly-6.0	1m 48s
Integration tests / nightly-main	17m 27s
Soundness / Documentation check	2m 3s
Cxx interop / nightly-main	1m 41s
Benchmarks / nightly-6.0	4m 58s
Soundness / License headers check	9s
Soundness / Broken symlinks check	2s
Soundness / Format check	0s
Benchmarks / nightly-main	5m 1s
Soundness / Unacceptable language check	3s
Unit tests / 5.8	3m 17s
Unit tests / 5.9	3m 18s
Unit tests / 5.10	3m 16s
Unit tests / nightly-6.0	4m 16s
Unit tests / nightly-main	4m 9s
	2h 6m 24s

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