mypy

gh-145990: sort `--help-env` sections by environment variable name (G… #19968

Job	Run time
Run mypy on Tools/cases_generator	18s
Run mypy on Lib/_pyrepl	17s
Run mypy on Lib/test/libregrtest	19s
Run mypy on Lib/tomllib	18s
Run mypy on Tools/peg_generator	17s
Run mypy on Tools/check-c-api-docs	17s
Run mypy on Tools/jit	17s
Run mypy on Tools/clinic	19s
Run mypy on Tools/build	17s
	2m 39s

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