mypy

gh-139103: fix free-threading `dataclass.init` perf issue (gh-141… #18036

Job	Run time
Run mypy on Tools/build	22s
Run mypy on Lib/_pyrepl	22s
Run mypy on Lib/test/libregrtest	18s
Run mypy on Tools/cases_generator	17s
Run mypy on Tools/clinic	17s
Run mypy on Tools/jit	19s
Run mypy on Lib/tomllib	17s
Run mypy on Tools/peg_generator	21s
	2m 33s

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