Add pre-commit plus a GItHub Action to run it

[cclauss]

As discussed at #718 (comment)

@akx Your review, please.

Using https://pre-commit.ci is even better than using GitHub Actions for pre-commit.

% pre-commit run --all-files

[INFO] Initializing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Initializing environment for https://github.com/charliermarsh/ruff-pre-commit.
[INFO] Initializing environment for https://github.com/abravalheri/validate-pyproject.
[INFO] Initializing environment for https://github.com/abravalheri/validate-pyproject:.[all].
[INFO] Installing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/charliermarsh/ruff-pre-commit.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/abravalheri/validate-pyproject.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
check builtin type constructor use.......................................Passed
check toml...............................................................Passed
check xml............................................(no files to check)Skipped
check yaml...............................................................Passed
ruff.....................................................................Passed
Validate pyproject.toml..................................................Passed

[akx]

This really boils down to maintainer (@PierreF) preference. #770 already set up running Ruff with tox, which is also fine. Left a comment about https://github.com/pre-commit/action in case you weren't aware of it.

[akx]

Suggested change

	- uses: actions/setup-python@v5
	with:
	python-version: 3.x
	- run: pip install pre-commit
	- run: pre-commit --version
	- run: pre-commit install
	- run: pre-commit run --all-files
	- uses: actions/setup-python@v5
	with:
	python-version: 3
	- uses: pre-commit/action@v3.0.0

[cclauss]

https://github.com/pre-commit/action is in maintenance-only mode and will not be accepting new features so I tend not to use it. pre-commit.ci is awesome.

[akx]

I know it's in maintenance-only mode, but it works – it's also just, well, 20 lines.

I don't prefer pre-commit.ci because it's a third-party dependency and (AFAIU) an one-man project (and for projects where "auto-fix PRs" is enabled, they tend to mess with my workflow).

[cclauss]

pre-commit.ci is run by the same person who led the development of pre-commit.

If auto-fix PRs are messing up your workflow then you do not have pre-commit properly installed locally.

[akx]

@cclauss Well, for a repo like this where every commit should have a --signoff to adhere to a CLA, the pre-commit commit wouldn't be appropriate, etc. 😁

[PierreF]

This add another tools for checking code, but I think it's okay:

• tox -e py (or just tox / tox -e py38): is here to run Python tests. And might took some time
• tox -e lint will be kept for slow linter
• pre-commit will be used for faster linter

Those linters/tests could still run locally and in Github actions. Which fit the needs of everyone:

• the one that want to run it locally (like me) before pushing to Github
• all PRs and master is also automatically checked by Github

[PierreF]

The error isn't added by the PR but already present on master. I will fix it once merged.

[akx]

Weak review comment, can be addressed later as well: If this is adopted (and I'm for it, in general), tox -e lint should just run pre-commit run --all-files to avoid drift between multiple lint styles.