Ignore typeshed test files (#17249) #12388

Job	Run time
Test suite with py38-ubuntu, mypyc-compiled	17m 32s
Test suite with py38-windows-64	19m 17s
Test suite with py39-ubuntu	16m 43s
Test mypyc suite with 32-bit Python	7m 11s
Test suite with py310-ubuntu	15m 0s
Test suite with py311-ubuntu, mypyc-compiled	15m 28s
Test suite with py312-ubuntu, mypyc-compiled	17m 56s
mypyc runtime tests with py39-macos	4m 17s
mypyc runtime tests with py38-debug-build-ubuntu	4m 44s
Type check our own code (py38-ubuntu)	1m 55s
Type check our own code (py38-windows-64)	2m 37s
Formatting and code style with Black + ruff	44s
	2h 3m 24s

Provide feedback