Add ruff as a linter

[nathanjmcdougall]

Given that pylint might be removed( #812), is it worth giving ruff a go instead?

Two of the big advantages over pylint are speed and auto-fix options being available for many of the rules.

Ruff has also implemented all of isort's rules, so isort could potentially be unnecessary.

I'm happy to have a go at introducing it (gently).