Tests

[ENH] Refactor `Extension` #1741

Job	Run time
docker	2s
(windows-latest, Py, sk0.24.*, sk-only:false)	4s
(ubuntu-latest, Py3.8, sk0.23.1, sk-only:false)	3s
(ubuntu-latest,Py3.10,sk1.4.*,sk-only:true)	54s
(ubuntu-latest,Py3.10,sk1.5.*,sk-only:true)	59s
(ubuntu-latest,Py3.11,sk1.3.*,sk-only:true)	59s
(ubuntu-latest,Py3.10,sk1.6.*,sk-only:true)	54s
(ubuntu-latest,Py3.11,sk1.4.*,sk-only:true)	54s
(ubuntu-latest,Py3.11,sk1.7.*,sk-only:true)	54s
(ubuntu-latest,Py3.10,sk1.7.*,sk-only:true)	1m 8s
(ubuntu-latest,Py3.12,sk1.5.*,sk-only:true)	1m 3s
(ubuntu-latest,Py3.13,sk1.6.*,sk-only:true)	59s
(ubuntu-latest,Py3.14,sk1.6.*,sk-only:true)	4m 14s
(ubuntu-latest,Py3.13,sk1.5.*,sk-only:true)	1m 1s
(ubuntu-latest,Py3.12,sk1.3.*,sk-only:true)	1m 2s
(ubuntu-latest,Py3.13,sk1.7.*,sk-only:true)	1m 2s
(ubuntu-latest,Py3.14,sk1.7.*,sk-only:true)	1m 9s
(ubuntu-latest,Py3.12,sk1.5.*,sk-only:false)	6m 26s
(windows-latest,Py3.12,sk1.5.*,sk-only:false)	4m 5s
(ubuntu-latest,Py3.12,sk1.6.*,sk-only:true)	1m 1s
(ubuntu-latest,Py3.11,sk1.6.*,sk-only:true)	53s
(ubuntu-latest,Py3.11,sk1.5.*,sk-only:true)	55s
(ubuntu-latest,Py3.12,sk1.4.*,sk-only:true)	1m 0s
(ubuntu-latest,Py3.12,sk1.7.*,sk-only:true)	1m 3s
(ubuntu-latest,Py3.14,sk1.5.*,sk-only:true)	4m 12s
(ubuntu-latest,Py3.14,sk1.7.*,sk-only:false)	3m 14s
(ubuntu-latest,Py3.10,sk1.3.*,sk-only:true)	59s
	41m 9s

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