Split out test-windows-cross to speed up ci #4108

Job	Run time
Check ${{ matrix.platform.target }}	0s
Test Alpine Linux	0s
Generate Matrix	5s
Test Auditwheel	0s
Test Cross Compile	0s
Test Docker	0s
Test Bootstrap (ubuntu-latest)	2m 27s
Test downstream - ${{ matrix.downstream.repository }}	0s
Test Bootstrap (macos-14)	3m 14s
Test Emscripten	0s
Test Bootstrap (windows-latest)	7m 5s
Test MSRV	1m 59s
Test windows cross	20m 25s
Test (ubuntu-latest, 3.12)	9m 52s
Test (ubuntu-latest, pypy3.10)	10m 29s
Test (macos-14, 3.12)	9m 16s
Test (windows-latest, 3.12)	19m 13s
Test (windows-latest, pypy3.10)	18m 49s
conclusion	1s
	1h 42m 55s

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