Inconsistent Python version constraints in documentation

[mhauru]

It seems that Python 3.10 is currently the highest Python version supported. However, there are a few places in the documentation that still say 3.8 or 3.9 is the highest. Not sure if the lower version bounds are more up to date, some places say 3.6, others 3.8, but not sure what the right one is. Here's a list of places where I saw this. I might have missed some, so might be worth a grep.

augur/docs/source/getting-started/installation.rst

Line 28 in a786ac5

**Python 3.9 is not yet supported because TensorFlow, which we use in our machine learning workers, does not yet support Python 3.9.**

augur/docs/source/getting-started/installation.rst

Line 24 in a786ac5

- `Python 3.6 - 3.8 <https://www.python.org/downloads/>`__

augur/README.md

Line 40 in a786ac5

Augur supports Python3.6 through Python3.9 on all platforms. Python3.10 and above do not yet work because of machine learning worker dependencies. On OSX, you can create a Python 3.9 environment this way: `python3.9 -m venv path/to/venv`.

augur/setup.py

Line 33 in a786ac5

"Programming Language :: Python :: 3.8",

augur/augur/tasks/git/util/facade_worker/setup.py

Line 45 in a786ac5

'Programming Language :: Python :: 3.7',

augur/augur/tasks/data_analysis/pull_request_analysis_worker/setup.py

Line 44 in a786ac5

'Programming Language :: Python :: 3.7',

augur/augur/tasks/data_analysis/contributor_breadth_worker/setup.py

Line 42 in a786ac5

'Programming Language :: Python :: 3.7',

augur/augur/tasks/data_analysis/discourse_analysis/setup.py

Line 50 in a786ac5

'Programming Language :: Python :: 3.7',

augur/augur/tasks/data_analysis/clustering_worker/setup.py

Line 43 in a786ac5

'Programming Language :: Python :: 3.7',

augur/augur/tasks/data_analysis/message_insights/setup.py

Line 55 in a786ac5

'Programming Language :: Python :: 3.7',

augur/augur/tasks/data_analysis/insight_worker/setup.py

Line 46 in a786ac5

'Programming Language :: Python :: 3.7',

augur/augur/tasks/git/util/facade_worker/setup.py

Line 45 in a786ac5

'Programming Language :: Python :: 3.7',

augur/scripts/install/checks.sh

Line 43 in a786ac5

echo "Please install Python 3.6 or higher to either python or python3."

augur/docs/source/development-guide/make/testing.rst

Line 52 in a786ac5

The above command runs all tests under all currently supported versions of **Python 3.6 and above**.