mypy

gh-142724: fix error path in `_PyPegen_raise_tokenizer_init_error` (#… #18517

Job	Run time
Run mypy on Lib/_pyrepl	20s
Run mypy on Tools/peg_generator	20s
Run mypy on Lib/tomllib	18s
Run mypy on Tools/cases_generator	18s
Run mypy on Tools/clinic	17s
Run mypy on Lib/test/libregrtest	20s
Run mypy on Tools/build	21s
Run mypy on Tools/jit	20s
	2m 34s

Provide feedback