limit docstrings and comments to 79 characters

[fohrloop]

This project has followed the following convention from the start:

• code limited to 88 characters (Black code style)
• Docstrings and comments limited to 79 characters.

Enforce this by adding the rule W505 for ruff.

Thoughts

Although the exact numbers (79 and 88) could also be something else
and still offer a good developer (and code reading) experience, those
numbers are pretty close to optimal. The reason for this is that I,
among many others develop on small screen (laptop). I also use a large
font / small resolution (which makes font larger) to make it easier for
my eyes. As it's pretty common to need to have code side by side, the
roughly 88 characters starts to be absolute maximum so one does not need
to do horizontal scrolling.

There must be some reason people like to have shorter docstrings than
the actual code.

• PEP8: 72 for comments, 79 for code
• Django code style: 79 for comments, 88 for code.

Could perhaps some day use same line length for code and comments, but
even with the 79 char limit the experience has been quite good and the
code looks easy to read in my opinion.

Refs:
https://peps.python.org/pep-0008/
https://docs.djangoproject.com/en/dev/internals/contributing/writing-code/coding-style