mypy

gh-151428: Remove unused imports in the stdlib (#151440) #21889

Job	Run time
Run mypy on Lib/test/libregrtest	23s
Run mypy on Tools/check-c-api-docs	17s
Run mypy on Lib/_pyrepl	18s
Run mypy on Tools/jit	18s
Run mypy on Tools/clinic	20s
Run mypy on Tools/cases_generator	19s
Run mypy on Tools/peg_generator	17s
Run mypy on Tools/build	18s
Run mypy on Lib/tomllib	17s
	2m 47s

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