mypy

gh-152674: Avoid quadratic behavior in xml.etree.ElementPath index pr… #22818

Job	Run time
Run mypy on Lib/tomllib	21s
Run mypy on Lib/_pyrepl	20s
Run mypy on Tools/jit	22s
Run mypy on Lib/test/libregrtest	17s
Run mypy on Tools/check-c-api-docs	12s
Run mypy on Tools/clinic	16s
Run mypy on Tools/cases_generator	23s
Run mypy on Tools/build	14s
Run mypy on Tools/peg_generator	21s
	2m 46s

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