Require Cython to be found #1080

Job	Run time
checks / other-checks	30s
checks / check-style	2m 1s
conda-cpp-build / compute-matrix	2s
conda-cpp-build / 11.8.0, 3.10, amd64, rockylinux8	3m 35s
conda-cpp-build / 12.5.1, 3.10, amd64, rockylinux8	2m 46s
conda-cpp-build / 11.8.0, 3.10, arm64, rockylinux8	2m 54s
conda-cpp-build / 12.5.1, 3.10, arm64, rockylinux8	2m 34s
docs-build / build	1m 26s
conda-cpp-tests / compute-matrix	2s
conda-cpp-tests / 11.8.0, 3.10, amd64, rockylinux8, v100, earliest-driver, oldest-deps	16m 25s
conda-cpp-tests / 12.5.1, 3.12, amd64, ubuntu24.04, v100, latest-driver, latest-deps	16m 6s
conda-cpp-tests / 12.0.1, 3.11, arm64, ubuntu20.04, a100, latest-driver, latest-deps	13m 50s
pr-builder	0s
	1h 2m 11s

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