Exclude ruff on vendored directories. #3654

Job	Run time
test_cygwin (39, windows-latest)	14m 24s
test (3.8, ubuntu-latest)	4m 13s
collateral (diffcov)	6m 41s
test (3.8, macos-latest)	5m 32s
collateral (docs)	1m 0s
test (3.8, windows-latest)	11m 13s
test (3.11, ubuntu-latest)	4m 7s
test (3.11, macos-latest)	7m 28s
test (3.11, windows-latest)	11m 5s
test (3.12, ubuntu-latest)	5m 44s
test (3.12, macos-latest)	7m 53s
test (3.12, windows-latest)	12m 18s
test (3.9, ubuntu-latest)	4m 11s
test (3.10, ubuntu-latest)	4m 1s
test (pypy3.10, ubuntu-latest, stdlib)	6m 39s
test (ubuntu-latest, 3.10, stdlib)	3m 56s
integration-test	0s
check	2s
release	0s
	1h 50m 27s

Provide feedback