Add prek GitHub Action

[jclarkeSTFC]

This adds a workflow to run prek on a PR. prek is a Rust version of pre-commit, see here.

It will run all the hooks in the existing .pre-commit-config.yaml file.

If it has produced fixes, then those are committed to the PR branch.

Once this is in we can delete the pre-commit job.

To test:

This is a PR on my fork where you can see me making a formatting change and prek fixing it, jclarkeSTFC#2

---

Reviewer

Your comments will be used as part of the gatekeeper process. Comment clearly on what you have checked and tested during your review. Provide an audit trail for any changes requested.

As per the review guidelines:

• Is the code of an acceptable quality? (Code standards/GUI standards)
• Has a thorough functional test been performed? Do the changes handle unexpected input/situations?
• Are appropriately scoped unit and/or system tests provided?
• Do the release notes conform to the guidelines and describe the changes appropriately?
• Has the relevant (user and developer) documentation been added/updated?
• If the PR author isn’t in the mantid-developers or mantid-contributors teams, add a review comment rerun ci to authorize/rerun the CI

Gatekeeper

As per the gatekeeping guidelines:

• Has a thorough first line review been conducted, including functional testing?
• At a high-level, is the code quality sufficient?
• Are the base, milestone and labels correct?

[jhaigh0]

Looks good to me. Are we going to replace this locally somehow too?

[jclarkeSTFC]

Yeah I'd suggest swapping out pre-commit for prek in the mantid-developer recipe, allegedly it's a drop-in replacement. I'm not sure if we actually want to merge this PR though, it was a bit of a test/demo, but I think it works fine if we decide to swap.

@thomashampson what do you think?

[sf1919]

I think this is probably one for the next TWG.... @peterfpeterson ?

[thomashampson]

Where the current pre-commit PR job configured?

[peterfpeterson]

@thomashampson got to https://pre-commit.ci/, login, and enable/disable the repository. Otherwise, the configuration itself is at the top of .pre-commit-config.yaml

$ head ~/code/mantid/.pre-commit-config.yaml 
default_language_version:
  python: python3

exclude: ^$|instrument/

ci:
  autofix_prs: true