Fixing non-second timedelta64 bug #428

Job	Run time
mypy	3m 49s
py3.13 \| macos \| unit tests	11m 29s
py3.13 \| macos \| integration tests	14m 46s
py3.13 \| ubuntu \| unit tests	13m 4s
py3.13 \| ubuntu \| integration tests	17m 8s
py3.13 \| windows \| unit tests	22m 20s
py3.13 \| windows \| integration tests	31m 12s
py3.10 \| ubuntu \| unit tests	12m 42s
py3.10 \| ubuntu \| integration tests	17m 35s
py3.11 \| ubuntu \| unit tests	12m 55s
py3.12 \| ubuntu \| unit tests	14m 28s
merge-test-artifacts	3s
	2h 51m 31s

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