we always load as cftime objects, never as datetime64(ns). Avoids err…

[JanStreffing]

Closes #151 by enforcing cfdate objects for all loaded datasets.

[koldunovn]

Tests are failing. Jan, can you have a look what might be wrong?

[JanStreffing]

I looked at those. I don't know why the mf open fails in the tests.

pyfesom2\load_mesh_data.py:520: in get_data
    dataset = xr.open_mfdataset(paths, combine="by_coords", cftime=True, **kwargs)
C:\Miniconda\envs\pyfesom2\lib\site-packages\xarray\backends\api.py:913: in open_mfdataset
    datasets = [open_(p, **open_kwargs) for p in paths]
C:\Miniconda\envs\pyfesom2\lib\site-packages\xarray\backends\api.py:913: in <listcomp>
    datasets = [open_(p, **open_kwargs) for p in paths]

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E       TypeError: open_dataset() got an unexpected keyword argument 'cftime'

/usr/share/miniconda/envs/pyfesom2/lib/python3.7/site-packages/xarray/backends/api.py:501: TypeError

It worked in my python 3.6.8 installation on juwels.

[koldunovn]

@JanStreffing what is the version of your xarray installation? The one installed by CI is 0.19.0 (the latest one from my understanding).

[JanStreffing]

@JanStreffing what is the version of your xarray installation? The one installed by CI is 0.19.0 (the latest one from my understanding).

Looks ok

# Name                    Version                   Build  Channel
xarray                    0.19.0             pyhd8ed1ab_1    conda-forge