Add matrix for Python and Debian versions

[duffn]

This no longer works with a single matrix of Python and Debian versions. For example, there's no python:3.11.5-buster since buster is older now: https://github.com/duffn/python-poetry/actions/runs/6433634454/job/17475594782.

So, the repo is going to need to a matrix of Python and Debian versions to continue to operate properly.