mypy

gh-145177: Fix Emscripten help text (#150874) #21715

Job	Run time
Run mypy on Tools/check-c-api-docs	18s
Run mypy on Tools/peg_generator	20s
Run mypy on Tools/build	21s
Run mypy on Lib/_pyrepl	17s
Run mypy on Tools/cases_generator	18s
Run mypy on Lib/tomllib	20s
Run mypy on Lib/test/libregrtest	19s
Run mypy on Tools/clinic	18s
Run mypy on Tools/jit	22s
	2m 53s

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