Fix requires in setup.cfg

[zmoon]

• removed setuptools from install_requires
• setup_requires info is specified in pyproject.toml, so removed it
• added initial groups for cftime and numpy_groupies

[rabernat]

Thanks a lot for this PR @zmoon! LGTM!

[rabernat]

Would be nice to document these options in the documentation somewhere.

[zmoon]

Yeah, and maybe iso would be a more intuitive name for the agg one since it is only used for the isotropic functions. Also currently numpy_groupies is required for isotropize, so maybe it should be a required dep, or instead a fallback to xarray groupby-bins should be implemented. Or wait, since it seems like xarray may support numpy-groupies for groupby in the near future.

[roxyboy]

Indeed, we will only depend on numpy_groupies until it is incorporated in xarray upstream.

[roxyboy]

So, I guess I'll merge this along with #168 ?

[zmoon]

I still have a bit more I want to do in #168. And there is still the question of the MITgcm data file. But I guess that could be separate.

[roxyboy]

I still have a bit more I want to do in #168. And there is still the question of the MITgcm data file. But I guess that could be separate.

Ok, in that case, I'll merge just #171