mypy

gh-148169: Fix webbrowser `%action` substitution bypass of dash-prefi… #20691

Job	Run time
Run mypy on Tools/build	20s
Run mypy on Lib/_pyrepl	21s
Run mypy on Tools/check-c-api-docs	15s
Run mypy on Tools/jit	19s
Run mypy on Tools/cases_generator	17s
Run mypy on Lib/test/libregrtest	20s
Run mypy on Lib/tomllib	16s
Run mypy on Tools/clinic	19s
Run mypy on Tools/peg_generator	19s
	2m 46s

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