Lint and typecheck fixes

[null-domain]

Summary

• Various linting fixes
• Ruff has been installed and replaces isort
• Slotscheck has been installed to verify correct __slots__ usage
• nox -s sphinx is no longer a default session
• Github Actions workflows no longer run on dependabot branches, only on PRs and pushes
• nox -s format has been renamed nox -s format_check - the format session name implied that it would format code, not check the formatting. nox -s format_fix still exists and does exactly this.

Additional but irrelevant info

You'll notice in a previous commit, pyproject.toml had a block for pyright configuration, and pyright was a default session in noxfile.py - originally I did want to migrate lightbulb to using pyright, as personally I feel it's a bit more strict with enforcing good practice (and, while biased, pyright maintainers themselves certainly seem to think so too) - not to mention that it updates and incorporates typing changes quicker than mypy does, and is in general faster with typechecking.

However, running pyright on lightbulb raises a shit ton of different errors and warnings that would take far too long to deal with. Mypy doesn't complain (which, it could be argued, isn't a great thing), so we'll stick with what works for now.

Checklist

• I have run nox and all the pipelines have passed.