Address Issue 128 (Read the Docs builds are Failing)

[danloveg]

Fixed by reverting to Python 3.8. Python 3.11 is not available in readthedocs.org yet.

Documentation is verified to be working here:

https://secure-record-transfer.readthedocs.io/en/issue-128/index.html

The link above may be broken in the future.

Closes #128