Split out test-windows-cross to speed up ci #4100

Job	Run time
Generate Matrix	4s
Test Emscripten	0s
Test Alpine Linux	0s
Test Auditwheel	0s
Test Cross Compile	0s
Test Docker	0s
Test MSRV	1m 49s
Test Bootstrap (ubuntu-latest)	3m 45s
Check ${{ matrix.platform.target }}	0s
Test downstream - ${{ matrix.downstream.repository }}	0s
Test Bootstrap (macos-14)	3m 15s
Test Bootstrap (windows-latest)	7m 56s
Test windows cross	5s
Test (ubuntu-latest, 3.12)	11m 49s
Test (ubuntu-latest, pypy3.10)	12m 27s
Test (macos-14, 3.12)	9m 49s
Test (windows-latest, 3.12)	22m 58s
Test (windows-latest, pypy3.10)	21m 6s
conclusion	1s
	1h 35m 4s

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