Have prepare_project exit on old versions of pip

[jeremykubica]

Change Description

Closes #333. Check the version of pip at the start of .prepare_project.sh and exit if the user is not using at least version 22.

Checklist

• This PR is meant for the lincc-frameworks/python-project-template repo and not a downstream one instead.
• This change is linked to an open issue
• This change includes integration testing, or is small enough to be covered by existing tests

[drewoldag]

This looks ok to me. I was able to test on a WSL system, and if you tested on mac, then we should be good.

Minor point - would it make sense to make the minimum pip version a variable? i.e. MIN_PIP_VERSION = 22? I'm not sure we'll be hunting around for it, but, since this is a user facing script, perhaps the extra clarity would nice.

[drewoldag]

If you have a moment, it might also be nice to update the getting started page that references the requirements - https://lincc-ppt.readthedocs.io/en/latest/source/overview.html#prerequisites

We call out pipx as an optional tool, we should probably call out pip >= 22 as well.

[jeremykubica]

I made the minimum pip version a variable and added the documentation as suggested. Thanks.

In doing so, I had a question: Does .prepare_project.sh use pipx if that is installed? Would the script still work if there is an old version of pip but a new version of pipx? If so, I can change the script to check for pipx first.

[drewoldag]

I've already chatted with Jeremy about this, but to answer the question in a more visible space - .prepare_project.sh should just use pip, not pipx. This is because pipx will install the project (and dependencies) such that it becomes available to all virtual environments.