GitHub Action to lint Python code

[cclauss]

• https://docs.github.com/en/actions
• https://docs.github.com/en/actions/use-cases-and-examples/building-and-testing/building-and-testing-python
• https://docs.astral.sh/ruff

The googletest vendored into this codebase was never ported to Python 3, so it has at least 64 files containing Python Syntax Errors. It should be re-vendored or removed if it is no longer used.

[mwallnoefer]

First of all, thanks for the contribution. I have managed to run it over the merge functionality and it catches all those Python 3 incompatibilities mentioned by you.

The point I wanted to raise is that this code base is pretty much maintenance-only. If I have understood it correctly, accepting this PR requests us to sort out all those Python 3 incompatibilities, otherwise we may not accept other fixes/patches respectively PRs.

I am not sure if it is really worth it, given that the codebase is old (e.g. we do also not support Mqtt 5.x), so I put also the other maintainers in the CC to hear their opinions.

@ejvr , @KonstantinRitt What do you think?

[ejvr]

We're not using python for anything in this repo, as far as I know. If all offending files are part of googletest, I'd propose we either update those files to the latest version of googlet test, of remove the code (if someone wants to run the test, the test app should be linked agaoinst an existing external library).