mypy

gh-151540: Use a selector event loop in the happy-eyeballs tests (#15… #22457

Job	Run time
Run mypy on Tools/cases_generator	32s
Run mypy on Tools/check-c-api-docs	30s
Run mypy on Tools/build	32s
Run mypy on Lib/tomllib	30s
Run mypy on Tools/jit	33s
Run mypy on Lib/_pyrepl	29s
Run mypy on Tools/clinic	29s
Run mypy on Tools/peg_generator	32s
Run mypy on Lib/test/libregrtest	36s
	4m 43s

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