Arraymancer CI

Fix "imported and not used: 'datatypes' [UnusedImport]" warning (#644) #427

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Job	Run time
linux-amd64-c (version-1-6)	6m 23s
macos-amd64-c (version-1-6)	9m 29s
linux-amd64-c (version-2-0)	7m 33s
macos-amd64-c (version-2-0)	11m 55s
linux-amd64-c (devel)	6m 23s
macos-amd64-c (devel)	12m 12s
	53m 55s