mypy

gh-149083: Convert dataclasses.MISSING and dataclasses.KW_ONLY to sen… #10490

Job	Run time
Run mypy on Lib/test/libregrtest	15s
Run mypy on Tools/jit	20s
Run mypy on Lib/_pyrepl	21s
Run mypy on Tools/cases_generator	19s
Run mypy on Tools/build	14s
Run mypy on Lib/tomllib	19s
Run mypy on Tools/check-c-api-docs	17s
Run mypy on Tools/peg_generator	15s
Run mypy on Tools/clinic	27s
	2m 47s

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