Tests

Fix inference when unpacking union type #17250

Job	Run time
Test mypyc suite with 32-bit Python	8m 5s
Test suite with py313-ubuntu, mypyc-compiled	13m 39s
Test suite with py314-dev-ubuntu	14m 52s
Test suite with py39-ubuntu, mypyc-compiled	1m 17s
Test suite with py312-ubuntu, mypyc-compiled	13m 6s
mypyc runtime tests with py39-macos	5m 18s
Test suite with py311-ubuntu	9m 0s
Test suite with py310-ubuntu	11m 39s
Type check our own code (py39-windows-64)	2m 11s
Test suite with py313-windows-64	22m 1s
Type check our own code (py39-ubuntu)	1m 32s
Formatting and code style with Black + ruff	1m 44s
	1h 44m 24s

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