Tests

Fix crashes caused by typevarlikes defaults in-place modifications (#… #19432

Job	Run time
Test mypyc suite with 32-bit Python	9m 54s
Test suite with py310-ubuntu	12m 34s
Test suite with py313-ubuntu, mypyc-compiled	14m 29s
Test suite with py312-ubuntu, mypyc-compiled	13m 52s
Test suite with py311-ubuntu	9m 25s
Test suite with py39-ubuntu, mypyc-compiled	16m 10s
Test suite with py314-ubuntu, mypyc-compiled	14m 22s
Type check our own code (py39-ubuntu)	1m 45s
Formatting and code style with Black + ruff	1m 54s
Test suite with py314-windows-64	25m 54s
mypyc runtime tests with py313-macos	5m 19s
mypyc runtime tests with py310-ubuntu	4m 46s
Type check our own code (py39-windows-64)	2m 14s
	2h 12m 38s

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