tests

Fix all mypy issues #3983

Job	Run time
test (3.8, ubuntu-latest)	3m 40s
test (3.8, macos-latest)	6m 4s
test (3.8, windows-latest)	8m 42s
test (3.11, ubuntu-latest)	4m 6s
test_cygwin (39, windows-latest)	14m 28s
test (3.11, macos-latest)	11m 25s
collateral (diffcov)	5m 59s
test (3.11, windows-latest)	13m 26s
collateral (docs)	57s
test (3.12, ubuntu-latest)	5m 53s
test (3.12, macos-latest)	15m 20s
test (3.12, windows-latest)	10m 14s
test (3.9, ubuntu-latest)	4m 21s
test (3.10, ubuntu-latest)	3m 56s
test (pypy3.10, ubuntu-latest, stdlib)	6m 47s
test (ubuntu-latest, 3.10, stdlib)	3m 39s
integration-test	0s
check	2s
release	0s
	1h 58m 59s

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