Enable E501 - line too long lint

[adamsardar]

What

Remove any mentions of ignoring E501 from the ruff configuration so that line length is controlled once again, in the same that black once did (ideally set to 88 to maintain the standard).

Why

Overlong lines can hurt readability. PEP 8, for example, recommends limiting lines to 79 characters. See the ruff documentation for the rule.

How

As mentioned in #169, where E501 support was attempted:

E501 line length - apparently 88 is the line length preferred by black but with this set it was suggesting editing a lot of lines in supposedly black approved code

The task of this ticket is to figure out what is going wrong (if anything) and bring the codebase back into support with E501 enabled.