mypy

gh-128974: Fix `UnicodeError.str` when custom attributes have sid… #68

Job	Run time
Run mypy on Lib/_pyrepl	15s
Run mypy on Lib/test/libregrtest	16s
Run mypy on Tools/build	12s
Run mypy on Tools/cases_generator	12s
Run mypy on Tools/clinic	14s
Run mypy on Tools/jit	14s
Run mypy on Tools/peg_generator	17s
Run mypy on Tools/wasm	17s
	1m 57s

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