Add yml linter

[ahuber21]

I noticed inconsistent configuration of yml autoformatters, so I added a formatter to the pre-commit hooks.

[mihaic]

Great idea! Can we use another repo? The pre-commit mirror repo has been archived.

[ahuber21]

How about using ymlfmt instead, which is based on ruamel.yaml
https://yaml.dev/doc/ruamel.yaml/

[mihaic]

How about using ymlfmt instead, which is based on ruamel.yaml https://yaml.dev/doc/ruamel.yaml/

It looks like it is not keeping up with ruamel.yaml development:

    'ruamel.yaml >=0.16.10, <=0.17.21',

https://github.com/jumanjihouse/pre-commit-hook-yamlfmt/blob/master/setup.py#L12
https://pypi.org/project/ruamel.yaml/#history

I am not convinced by ymlfmt either but I will remove my change request in case someone else wants to approve.

No longer using the hook I objected to.

[ethanglaser]

No objections from my end. Seems like an industry standard tool with fairly typical args. Thanks for unifying

[ahuber21]

Okay, this time I went with check-yaml from pre-commit-hooks directly. The downside is that it's not able to format files that don't meet requirements. But it will still flag them of course.
Since I'm not able to find a well-maintained formatter hook, I suggest we go with linting only.

All yaml files still pass the check. I tested with

pre-commit run --all-files