Prepare for update to Python 3.11

[chakeson]

Here is a good overview of it https://docs.python.org/3.11/whatsnew/3.11.html
Most relevant is the 10-60% speed update, which would help the django backend. PEP 681 might also help with django part.

[ndepaola]

sounds good - i'd probably wait for the .1 release in case any bugs made it through to .0 :) looks like there aren't any breaking changes between 3.9 and 3.11 so this should be straightforward

[ndepaola]

fyi - not upgrading to 3.11 right now is motivated by trying to maintain windows 7 support for the desktop tool for as long as possible