mypy

gh-144001: Support ignoring the invalid pad character in Base64 decod… #19404

Job	Run time
Run mypy on Lib/tomllib	19s
Run mypy on Tools/build	22s
Run mypy on Tools/cases_generator	18s
Run mypy on Tools/clinic	20s
Run mypy on Tools/peg_generator	22s
Run mypy on Lib/_pyrepl	20s
Run mypy on Lib/test/libregrtest	23s
Run mypy on Tools/jit	18s
Run mypy on Tools/check-c-api-docs	21s
	3m 3s

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