Our setup.py wasn't updated prior to release to specify our current

version compatibility. We had dropped Python 3.5 support, and added

versions through 3.9. However, we didn't have anything in our setup.py

preventing Python 3.5 from use, or advertising modern 3.x support in the

version classifiers.
This change updates to ensure our package information and checks are

compliant with the current range of supported versions.

Attempted to build the package for Python 3.5. Saw the correct error

response.
Successfully built the package with Python 3.9 and checked the classifiers.