Enable checking for f strings #13131

Job	Run time
Test mypyc suite with 32-bit Python	6m 37s
Test suite with Python nightly	14m 12s
Test suite with py38-ubuntu, mypyc-compiled	17m 52s
Test suite with py38-windows-64	19m 47s
Test suite with py39-ubuntu	18m 58s
Test suite with py310-ubuntu	16m 21s
Test suite with py311-ubuntu, mypyc-compiled	15m 31s
Test suite with py312-ubuntu, mypyc-compiled	17m 39s
mypyc runtime tests with py39-macos	7m 11s
mypyc runtime tests with py38-debug-build-ubuntu	4m 26s
Type check our own code (py38-ubuntu)	1m 50s
Type check our own code (py38-windows-64)	2m 9s
Formatting and code style with Black + ruff	35s
	2h 23m 8s

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