[FEAT]: Add `pre-commit` hook

[adam-grant-hendry]

Could we please add a pre-commit hook for this project?

`.pre-commit-hooks.yaml

- id: poetry-relax
  name: poetry-relax
  description: A poetry plugin to relax dependency versions when publishing libraries.
  entry: poetry relax
  language: python
  language_version: python3
  pass_filenames: false
  files: ^pyproject.toml$

[zanieb]

Sounds good to me, but for https://github.com/astral-sh/ruff-pre-commit/ we had to put it in a separate repository and I don't remember why. I'm not sure if I want to maintain it if so because then I have to manage version bumps across repositories and there just aren't enough users of this project to merit it at this point.

[adam-grant-hendry]

@zanieb May I maintain it?

[zanieb]

@adam-grant-hendry yeah you're welcome to do so! If you want to create a repository we can link to it from the README here otherwise I could create the repository and add you as a maintainer.

[adam-grant-hendry]

I'm happy to make the repo and yes, let's link it in the README. I'll take a stab at it and report back 😉