Make a few cleanups:
- Remove python 2.7 stanza from setup.py
- Update classifiers
- Update requirements, no need for python_version anymore
Change-Id: I6b6dfb0959973abf0c2e8325006025db2a5d85d0
Some options are now automatically configured by the version 1.20:
- project
- html_last_updated_fmt
- latex_engine
- latex_elements
- version
- release.
Change-Id: I2577ca452a014402f1377474457095176d422b42
Sphinx 2.0 no longer works on python 2.7, so we need to start capping
it there as well
depend on https://review.opendev.org/#/c/657890/
Change-Id: Ic77e0db24ab7d7f068faf3e237beefa8856a710a