Enable checking for f strings #13130

Job	Run time
Test mypyc suite with 32-bit Python	6m 51s
Test suite with Python nightly	14m 16s
Test suite with py38-ubuntu, mypyc-compiled	17m 26s
Test suite with py38-windows-64	19m 51s
Test suite with py39-ubuntu	17m 9s
Test suite with py310-ubuntu	16m 6s
Test suite with py311-ubuntu, mypyc-compiled	15m 30s
Test suite with py312-ubuntu, mypyc-compiled	18m 8s
mypyc runtime tests with py39-macos	5m 10s
mypyc runtime tests with py38-debug-build-ubuntu	4m 38s
Type check our own code (py38-ubuntu)	1m 49s
Type check our own code (py38-windows-64)	2m 26s
Formatting and code style with Black + ruff	37s
	2h 19m 57s

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