This repo is now testing only with Python 3, so let's make
a few cleanups:
- Remove python 2.7 stanza from setup.py
- Add requires on python >= 3.6 to setup.cfg so that pypi and pip
know about the requirement
- Remove obsolete sections from setup.cfg
- Update requirements, no need for python_version anymore
- Use newer openstackdocstheme version
- Remove install_command from tox.ini, the default is fine
- Use TOX_CONSTRAINTS_FILE instead of UPPER_CONSTRAINTS_FILE since
the later is obsolete
- Increase lower constraints to fullfill package requests
Change-Id: I7126c2646f272b3f8c568630293a194bc5ba98a9
* setuptools can never upgrade things based on setup_requires versions
* actual pbr version range should be defined in requirements.txt
Change-Id: I45476eee5c7916e526635a52c0af8b251b736a05