mypy

gh-139551: add support for BaseExceptionGroup in IDLE (GH-139563) #20656

Job	Run time
Run mypy on Tools/cases_generator	18s
Run mypy on Lib/tomllib	19s
Run mypy on Tools/jit	22s
Run mypy on Tools/clinic	15s
Run mypy on Lib/_pyrepl	18s
Run mypy on Tools/build	16s
Run mypy on Lib/test/libregrtest	19s
Run mypy on Tools/check-c-api-docs	16s
Run mypy on Tools/peg_generator	19s
	2m 42s

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