Coordinate variables don't get units via pint-xarray #23
Description
Noticed this when doing ds.rams.lwp, the returned variables has units kilogram / meter**3 when the correct unit should be kilogram / meter**2. The unit of ds.zis not applied during ds.pint.quantify() so the .integrate('z') part of the LWP calculation does not affect the units.
This is a known issue with xarray and pint-xarray, as noted here https://pint-xarray.readthedocs.io/en/latest/generated/xarray.Dataset.pint.quantify.html#xarray-dataset-pint-quantify