Tests

Bump librt to 0.12.0 #22613

Job	Run time
Test mypyc suite with 32-bit Python	12m 12s
Test suite with py315-ubuntu, mypyc-compiled	15m 41s
Type check our own code (py310-windows-64)	1m 43s
Test suite with py314t-ubuntu, mypyc-compiled	18m 15s
Test suite with py310-ubuntu, mypyc-compiled	17m 33s
Parallel tests with py314-ubuntu, mypyc-compiled	29m 24s
Test suite with py311-ubuntu	9m 57s
Test suite with py314-windows-64	32m 48s
mypyc runtime tests with py310-ubuntu	7m 43s
Type check our own code (py310-ubuntu)	1m 3s
Test suite with py314-ubuntu, mypyc-compiled	16m 23s
Test suite with py312-ubuntu	9m 52s
mypyc runtime tests with py313-macos	6m 49s
Test suite with py313-ubuntu, mypyc-compiled	15m 58s
Parallel tests with py314-windows-64, interpreted	11m 3s
Parallel tests with py314-ubuntu, interpreted	26m 29s
Formatting and code style with Black + ruff	1m 44s
	3h 54m 37s

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