Fix run_tests.sh invocation

[nsoranzo]

Also:

• Drop support for Python 3.5
• Add support for Python 3.9
• Rebuild docs

[nsoranzo]

Depends on kislyuk/argcomplete#332 and a new argcomplete release on PyPI.

[nsoranzo]

Ready for review!

BTW, it looks to me that all test jobs in .circleci/config.yml are already run in GitHub workflows, can we drop the file? @jmchilton

[jmchilton]

There are a bunch of overlapping parameters to get more of these buggy tests working - I'd very much like to expand test coverage (more tests, more versions of Python, more versions of Galaxy, etc..) so I was working on trying to get those circleci tests working. I wouldn't delete the file - I'd like to keep working on it.

[jmchilton]

Thanks so much for the fix!