mypy

GH-126910: reserve FP on AArch64 when generating JIT stencils #20223

Job	Run time
Run mypy on Lib/_pyrepl	17s
Run mypy on Tools/build	20s
Run mypy on Tools/clinic	20s
Run mypy on Tools/cases_generator	21s
Run mypy on Tools/jit	17s
Run mypy on Tools/peg_generator	19s
Run mypy on Tools/check-c-api-docs	16s
Run mypy on Lib/tomllib	24s
Run mypy on Lib/test/libregrtest	22s
	2m 56s

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