mypy

gh-134837: Correct and improve base85 documentation for base64 and bi… #21300

Job	Run time
Run mypy on Tools/check-c-api-docs	31s
Run mypy on Tools/clinic	32s
Run mypy on Tools/cases_generator	30s
Run mypy on Tools/peg_generator	26s
Run mypy on Lib/test/libregrtest	34s
Run mypy on Lib/tomllib	24s
Run mypy on Tools/build	30s
Run mypy on Lib/_pyrepl	32s
Run mypy on Tools/jit	31s
	4m 30s

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