workaround for numpy checking string arrays found in sunraster #1865

Job	Run time
sdist_verify	15s
cron	-1s
core / Load tox environments	7s
core / py313 (ubuntu-latest)	1m 18s
test / Load tox environments	6s
docs / Load tox environments	9s
test / py312 (macos-latest)	1m 4s
test / py310-oldestdeps (ubuntu-latest)	1m 22s
test / py311 (windows-latest)	2m 27s
docs / build_docs (ubuntu-latest)	1m 41s
publish	0s
notify	0s
	8m 28s

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