Remove standalone pytest run_tests.py bundle Newer pytest doesn't support generating stand alone testing bundles. Python 3.9 generates errors running the current run_tests.py. Changed doc to use pythonX -m pytest test/ and some light directions on how to install pytest. Thanks to jerrykan for recommendations on how to do the doc updates.

#!/usr/bin/env python
import sys
import roundup

from roundup.demo import main

sys.exit(main())