Python version in base images is out of date

[niloc132]

The python version we get from debian since taking this approach to our images is down to 3.7.3, down from our previous 3.7.10 (latest is 3.7.13).

Ideally we should move back to 3.7.10 or something newer, and possibly track an upstream to ensure we stay up to date.

[devinrsmith]

At the current time, we are using the apt package manager with a base image of debian:buster-slim. Granted, this isn't the latest version of debian, but I wish that they would keep python 3.7.x up-to-date with the latest patch releases.

It's likely a reasonable thing to assume our own responsibility for building and shipping the "correct" python version - in essence, trying to divorce our major components from the release cycles of upstream package managers. (The same argument can be made for java.)

If we do, we may choose to assume cpython build responsibilities (https://devguide.python.org/setup/), or use helper tools that essentially do the same thing (https://github.com/pyenv/pyenv/blob/master/plugins/python-build/README.md).

There may be a larger conversation to be had about the matrix of python versions we support, and if we want to change our base image.