Fix sparse grid tests (#843) #1393

Job	Run time
runnable	0s
lint / lint	21s
test (3.9, true, true, ubuntu-latest)	7m 4s
test (3.9, true, true, macos-12)	8m 37s
test (3.9, true, false, ubuntu-latest)	6m 44s
test (3.9, true, false, macos-12)	9m 28s
test (3.9, true, false, macos-14)	4m 41s
test (3.9, false, false, ubuntu-latest)	5m 58s
test (3.9, false, false, macos-12)	10m 1s
test (3.9, false, false, macos-14)	3m 41s
test (3.12, true, false, ubuntu-latest)	7m 37s
test (3.12, true, false, macos-12)	9m 29s
test (3.12, true, false, macos-14)	6m 40s
	1h 20m 21s

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