mypy

gh-126676: Expand argparse docs for type=bool with warning and altern… #20386

Job	Run time
Run mypy on Lib/test/libregrtest	24s
Run mypy on Tools/cases_generator	16s
Run mypy on Tools/jit	19s
Run mypy on Lib/_pyrepl	19s
Run mypy on Tools/build	18s
Run mypy on Tools/clinic	19s
Run mypy on Lib/tomllib	19s
Run mypy on Tools/check-c-api-docs	18s
Run mypy on Tools/peg_generator	24s
	2m 56s

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