CI use 6.1 nightlies #21

Job	Run time
Cxx interop / Construct Cxx interop matrix	4s
Unit tests / Construct unit test matrix	4s
Soundness / Format check	30s
Soundness / API breakage check	3m 30s
Soundness / Documentation check	2m 22s
Soundness / Broken symlinks check	2s
Soundness / License headers check	3s
Soundness / Unacceptable language check	3s
Soundness / Python lint check	8s
Soundness / Shell check	56s
Soundness / YAML lint check	3s
Cxx interop / Swift 6 language mode	2m 12s
Unit tests / Unit tests / Linux (5.9)	2m 0s
Unit tests / Unit tests / Linux (5.10)	1m 55s
Unit tests / Unit tests / Linux (6.0)	2m 16s
Unit tests / Unit tests / Linux (nightly-6.1)	2m 39s
Unit tests / Unit tests / Linux (nightly-main)	2m 44s
Cxx interop / Cxx interop / Linux (5.9)	2m 2s
Cxx interop / Cxx interop / Linux (5.10)	1m 58s
Cxx interop / Cxx interop / Linux (6.0)	2m 15s
Cxx interop / Cxx interop / Linux (nightly-6.1)	2m 49s
Cxx interop / Cxx interop / Linux (nightly-main)	2m 45s
	33m 20s

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