dev: ignore generated cufile.pyx (#977) #3

Job	Run time
ci-vars	21s
Build ${{ matrix.host-platform }}, CUDA ${{ needs.ci-vars.outputs.CUDA_BUILD_VER }}	0s
Docs	0s
Test ${{ matrix.host-platform }}	0s
Test ${{ matrix.host-platform }}	0s
Check job status	-1s
	20s

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