mypy

GH-75949: Fix argparse dropping '|' in mutually exclusive groups on l… #18271

Job	Run time
Run mypy on Lib/test/libregrtest	17s
Run mypy on Lib/_pyrepl	25s
Run mypy on Tools/cases_generator	20s
Run mypy on Lib/tomllib	16s
Run mypy on Tools/jit	21s
Run mypy on Tools/clinic	19s
Run mypy on Tools/peg_generator	19s
Run mypy on Tools/build	17s
	2m 34s

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