Tests

Fix narrowing for unions #20658

Job	Run time
Test mypyc suite with 32-bit Python	9m 19s
Test suite with py314t-ubuntu, mypyc-compiled	16m 51s
Type check our own code (py310-windows-64)	2m 22s
Parallel tests with py314-ubuntu, mypyc-compiled	31m 16s
Test suite with py313-ubuntu, mypyc-compiled	13m 38s
Test suite with py310-ubuntu, mypyc-compiled	15m 44s
Test suite with py314-ubuntu, mypyc-compiled	14m 16s
Test suite with py312-ubuntu	8m 59s
mypyc runtime tests with py313-macos	6m 48s
Type check our own code (py310-ubuntu)	1m 41s
Test suite with py311-ubuntu	8m 55s
mypyc runtime tests with py310-ubuntu	5m 21s
Test suite with py314-windows-64	27m 26s
Parallel tests with py314-ubuntu, interpreted	22m 48s
Formatting and code style with Black + ruff	1m 55s
	3h 7m 19s

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