Tests

[ENH] Extend `Extension` class test suite #1641

Job	Run time
(ubuntu-latest, Py3.8, sk0.23.1, sk-only:false)	3s
docker	3s
(windows-latest, Py, sk0.24.*, sk-only:false)	2s
(ubuntu-latest, Py3.10, sk1.3.*, sk-only:true)	8m 2s
(ubuntu-latest, Py3.11, sk1.3.*, sk-only:true)	7m 10s
(ubuntu-latest, Py3.10, sk1.7.*, sk-only:true)	8m 3s
(ubuntu-latest, Py3.10, sk1.5.*, sk-only:true)	8m 6s
(ubuntu-latest, Py3.12, sk1.3.*, sk-only:true)	8m 2s
(ubuntu-latest, Py3.13, sk1.5.*, sk-only:true)	8m 3s
(ubuntu-latest, Py3.12, sk1.7.*, sk-only:true)	8m 5s
(ubuntu-latest, Py3.12, sk1.5.*, sk-only:false)	6h 0m 27s
(ubuntu-latest, Py3.10, sk1.6.*, sk-only:true)	8m 13s
(ubuntu-latest, Py3.12, sk1.4.*, sk-only:true)	7m 33s
(ubuntu-latest, Py3.11, sk1.4.*, sk-only:true)	8m 21s
(ubuntu-latest, Py3.12, sk1.6.*, sk-only:true)	7m 45s
(ubuntu-latest, Py3.12, sk1.5.*, sk-only:true)	8m 49s
(ubuntu-latest, Py3.11, sk1.7.*, sk-only:true)	7m 43s
(ubuntu-latest, Py3.11, sk1.5.*, sk-only:true)	7m 37s
(ubuntu-latest, Py3.11, sk1.6.*, sk-only:true)	7m 10s
(ubuntu-latest, Py3.13, sk1.7.*, sk-only:true)	7m 43s
(ubuntu-latest, Py3.13, sk1.6.*, sk-only:true)	8m 16s
(windows-latest, Py3.12, sk1.5.*, sk-only:false)	39m 44s
(ubuntu-latest, Py3.10, sk1.4.*, sk-only:true)	7m 18s
	9h 2m 18s

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