mypy

GH-138245: Perform boolean guards by testing a single bit, rather tha… #19202

Job	Run time
Run mypy on Lib/tomllib	17s
Run mypy on Tools/build	20s
Run mypy on Tools/cases_generator	20s
Run mypy on Tools/check-c-api-docs	16s
Run mypy on Lib/test/libregrtest	20s
Run mypy on Lib/_pyrepl	18s
Run mypy on Tools/peg_generator	20s
Run mypy on Tools/clinic	20s
Run mypy on Tools/jit	16s
	2m 47s

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