Tests

Add initial support for new style TypeVar defaults (PEP 696) #13642

Job	Run time
Test mypyc suite with 32-bit Python	7m 17s
Test suite with py38-ubuntu, mypyc-compiled	17m 52s
Test suite with py38-windows-64	19m 57s
Test suite with py39-ubuntu	16m 44s
Test suite with py310-ubuntu	15m 50s
Test suite with py311-ubuntu, mypyc-compiled	15m 29s
Test suite with py312-ubuntu, mypyc-compiled	17m 43s
Test suite with py313-ubuntu, mypyc-compiled	18m 5s
mypyc runtime tests with py39-macos	5m 41s
Type check our own code (py38-ubuntu)	1m 55s
Type check our own code (py38-windows-64)	2m 29s
Formatting and code style with Black + ruff	34s
	2h 19m 36s

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