Automatic formatting in CI

[danielhollas]

PR #24 proposed to use a ruff formatter for the code and enforce it in the CI.
Docs for ruff formatter
setup in PyCharm
From the PR description:

One advantage of ruff is that it is also a linter (although I am not setting up the linter here, am planning to discuss separately in a follow-up PR), so we would have a single tool for both.

Ruff uses a formatting style of another very common formatter called "black", and is quite different from what we have now. @JanosJiri if you have a strong preference for the current format, that is totally fine, but in that case you need to figure out which formater PyCharm uses in your setup so I can use it as well and we can enforce it in CI.

Besides the choice of the formatter, there are other things to be decided:

• line length: Right now I have configured maximum line length to 130 to preserve existing format. I would personally preferred a bit shorter lines, but it is entirely up to you. @JanosJiri perhaps you can experiment locally with configuring shorter lines and see what looks best to you.
• Do we use single or double quotes? The current code was inconsistent so I used ruff's default of double quotes, but I have no strong opinions on this, both are fine and it is configurable.

See Discussion in #24, it's unclear if we want this, given that the current formatting is very different from black / ruff.