python3-setuptools-opt (Install newer setuptools in /opt)

Setuptools is a fully-featured, actively-maintained, and stable
library designed to facilitate packaging Python projects.

Installs to /opt/python3.9/site-packages.

Add the following before the python3 build commands in your
Slackbuild to use this version over the stock one in 15.0:

export PYTHONPATH=/opt/python3.9/site-packages/