Add `setuptools` to dependencies

[devon-mar]

Fixes #917

setuptools 42.0.0 is the first version that supports Python 3.8, the minimum Python requirement.

[ktbyers]

@devon-mar Can you rebase and update the poetry.lock file? There were some other changes recently to the lock file.

[devon-mar]

@ktbyers Done

[ktbyers]

setuptools is no longer guaranteed to be installed in PY3.12 and later:

https://docs.python.org/3/whatsnew/3.12.html

[gh-95299](https://github.com/python/cpython/issues/95299): Do not pre-install setuptools 
in virtual environments created with [venv](https://docs.python.org/3/library/venv.html#module-venv). 
This means that distutils, setuptools, pkg_resources, and easy_install will no longer available by 
default; to access these run pip install setuptools in the 
[activated](https://docs.python.org/3/library/venv.html#venv-explanation) virtual environment.