The next Python release is scheduled for 2020-10-05.
We'll probably have to wait for it to be available on travis, though.

• Make sure pandas has a .whl for Python 3.9
• Make sure numpy has a .whl for Python 3.9
• ~test travis support~~ travis support is dropped in favor of GH actions.
• Add line to the meta in setup.py
• Changelog
• Contributing doc changes
• README.md changes
• Upgrade Python version for flake travis related