There should be a way to silence the DeprecationWarning

[greglucas]

We are currently getting these deprecation warnings:

DeprecationWarning: datetime64_to_cdftt2000 will eventually be phased out. Instead, datetime64 types will automatically be converted into a CDF time type. If you do not wish datetime64 arrays to be converted, cast them to a different type prior to calling xarray_to_cdf()

even when leaving out the keyword argument in the call. This is because there is a default keyword argument still in the signature which makes this case always hit.
https://github.com/MAVENSDC/cdflib/blob/88ba11e8613cefe9f35bf950e21b6ba276ee9693/cdflib/xarray/xarray_to_cdf.py#L1003-L1008

I think you might be able to add a **kwargs catch-all here for the deprecation warning and see if datetime64_to_cdftt2000 is in kwargs and issue the deprecation warning then.

[bryan-harter]

It's probably just time to phase it out. I can't imagine people would include a datetime64 numpy object and NOT want it to be a CDF time