`setuptools` needs to be added to install requirements

Was there a change from `distutils` to `setuptools` recently? The `python setup.py install` command fails with
```
Traceback (most recent call last):
  File "/sps/lsst/users/rsolomon/clevar/setup.py", line 1, in <module>
    from setuptools import setup, find_packages
ModuleNotFoundError: No module named 'setuptools'
```