tests

[CI] Set `PIP_PREFER_BINARY` in tox as a workaround for problems in macOS #6805

Job	Run time
collateral (docs)	2m 21s
collateral (diffcov)	3m 33s
test_cygwin (39, windows-latest)	14m 50s
Fail the job if files changed under _disutils/_vendor folders	11s
test (3.9, ubuntu-latest)	3m 26s
test (>=3.13.5, ubuntu-latest)	3m 26s
test (3.9, macos-latest)	3m 20s
test (>=3.13.5, macos-latest)	3m 25s
test (3.11, ubuntu-latest)	3m 11s
test (3.10, ubuntu-latest)	3m 25s
test (3.12, ubuntu-latest)	3m 26s
test (3.9, windows-latest)	3m 27s
test (>=3.13.5, windows-latest)	2m 57s
test (ubuntu-latest, 3.10, stdlib)	3m 25s
test (3.14, ubuntu-latest)	3m 28s
test (pypy3.10, ubuntu-latest, stdlib)	3m 26s
integration-test	0s
check	2s
release	-1s
	1h 1m 18s

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