Rename nightly_6_1 params to nightly_next #22

Job	Run time
Cxx interop / Construct Cxx interop matrix	2s
Unit tests / Construct unit test matrix	4s
Soundness / API breakage check	4m 30s
Soundness / Documentation check	3m 0s
Soundness / License headers check	3s
Soundness / Unacceptable language check	3s
Soundness / Broken symlinks check	3s
Soundness / Python lint check	4s
Soundness / Format check	30s
Soundness / Shell check	35s
Soundness / YAML lint check	5s
Cxx interop / Swift 6 language mode	2m 39s
Cxx interop / Cxx interop / Linux (5.9)	2m 39s
Cxx interop / Cxx interop / Linux (5.10)	2m 29s
Cxx interop / Cxx interop / Linux (6.0)	2m 55s
Cxx interop / Cxx interop / Linux (nightly-next)	3m 35s
Cxx interop / Cxx interop / Linux (nightly-main)	2m 43s
Unit tests / Unit tests / Linux (5.9)	2m 21s
Unit tests / Unit tests / Linux (5.10)	2m 22s
Unit tests / Unit tests / Linux (6.0)	2m 53s
Unit tests / Unit tests / Linux (nightly-next)	3m 24s
Unit tests / Unit tests / Linux (nightly-main)	2m 48s
	39m 47s

Provide feedback