Tests

Add more type annotations #672

Job	Run time
(ubuntu-latest, Py3.7, sk0.21.2, sk-only:true)	10m 3s
(ubuntu-latest, Py3.7, sk0.22.2, sk-only:true)	10m 40s
(ubuntu-latest, Py3.7, sk0.23.1, sk-only:true)	10m 44s
(ubuntu-latest, Py3.7, sk0.24, sk-only:true)	10m 43s
(ubuntu-latest, Py3.8, sk0.22.2, sk-only:true)	10m 55s
(ubuntu-latest, Py3.8, sk0.23.1, sk-only:true)	14m 44s
(ubuntu-latest, Py3.8, sk0.24, sk-only:true)	10m 34s
(ubuntu-20.04, Py3.6, sk0.18.2, sk-only:true)	48s
(ubuntu-20.04, Py3.6, sk0.19.2, sk-only:true)	44s
(ubuntu-20.04, Py3.6, sk0.20.2, sk-only:true)	42s
(ubuntu-20.04, Py3.6, sk0.21.2, sk-only:true)	41s
(ubuntu-20.04, Py3.6, sk0.22.2, sk-only:true)	47s
(ubuntu-20.04, Py3.6, sk0.23.1, sk-only:true)	43s
(ubuntu-20.04, Py3.6, sk0.24, sk-only:true)	44s
(ubuntu-latest, Py3.8, sk0.23.1, sk-only:false)	22m 51s
(windows-latest, Py, sk0.24.*, sk-only:false)	26m 58s
	2h 13m 21s

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