Fixing non-second timedelta64 bug #399

Job	Run time
mypy	3m 48s
py3.13 \| macos \| unit tests	8m 39s
py3.13 \| macos \| integration tests	13m 17s
py3.13 \| ubuntu \| unit tests	13m 7s
py3.13 \| ubuntu \| integration tests	17m 9s
py3.13 \| windows \| unit tests	19m 12s
py3.13 \| windows \| integration tests	31m 6s
py3.10 \| ubuntu \| unit tests	12m 58s
py3.10 \| ubuntu \| integration tests	17m 12s
py3.11 \| ubuntu \| unit tests	12m 47s
py3.12 \| ubuntu \| unit tests	13m 39s
merge-test-artifacts	2s
	2h 42m 56s

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