Tests

Fix slots issue with deferred base (#20573) #20119

Job	Run time
Test mypyc suite with 32-bit Python	9m 39s
Test suite with py310-ubuntu, mypyc-compiled	15m 20s
Test suite with py314-ubuntu, mypyc-compiled	14m 40s
Test suite with py313-ubuntu, mypyc-compiled	14m 42s
Test suite with py312-ubuntu	9m 59s
Parallel tests with py314-ubuntu, interpreted	22m 41s
mypyc runtime tests with py313-macos	5m 41s
Type check our own code (py310-ubuntu)	1m 46s
Test suite with py314t-ubuntu, mypyc-compiled	19m 35s
mypyc runtime tests with py310-ubuntu	5m 41s
Test suite with py311-ubuntu	9m 10s
Type check our own code (py310-windows-64)	2m 32s
Formatting and code style with Black + ruff	2m 3s
Test suite with py314-windows-64	27m 15s
Parallel tests with py314-ubuntu, mypyc-compiled	29m 19s
	3h 10m 3s

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