Add setuptools dependency

[hoechenberger]

A build of one of my packages, which depends on xarray, failed because setuptools doesn't get installed alongside xarray, yet xarray depends on setuptools. On the conda-forge gitter channel it was then suggested that the xarray recipe should explicitly list setuptools as a run dependency. This is what this PR does.

Checklist

• Used a fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[hoechenberger]

@conda-forge-admin, please rerender

[hoechenberger]

@shoyer Same should probably also be fixed upstream :) (INSTALL_REQUIRES in setup.py)

[ocefpaf]

Looks like the new HTML printing uses pkg_resources.

[hoechenberger]

Thanks @ocefpaf!

[shoyer]

Thanks for the fix. Could you kindly open an issue in the xarray issue tracker? A pull request would be even better :)

[crusaderky]

setuptools is not a runtime dependency since pydata/xarray#3720
Also, I'm confused - both conda and cpython always come with setuptools preinstalled. How did you manage to get an environment without it?

[crusaderky]

(please revert)

[hoechenberger]

@crusaderky setuptools at least doesn't get automatically installed on the conda-forge CI when the tests are run. I've created a PR that uses an xarray package version that doesn't have the setuptools dep, and the build fails: conda-forge/questplus-feedstock#10
This is why setuptools was added as a runtime dep. (This was suggested to me on the conda-forge gitter channel)

[crusaderky]

Ah I see now that it's required by xarray.core.formatting_html too.