mypy

Add missing backticks in os and decimal docs (#141699) #18023

Job	Run time
Run mypy on Lib/_pyrepl	19s
Run mypy on Tools/build	21s
Run mypy on Tools/cases_generator	16s
Run mypy on Lib/tomllib	23s
Run mypy on Tools/clinic	20s
Run mypy on Tools/jit	22s
Run mypy on Lib/test/libregrtest	19s
Run mypy on Tools/peg_generator	20s
	2m 40s

Provide feedback