Small improvements

[mkuf]

Please elaborate on what you are implementing with this PR and what it improves.

[hz61p1]

@mkuf

1. Adding a linter brings in generally accepted guidelines when writing yaml files
2. Adding docker image overrides via environment variable, so that you don't have to edit docker compose files if you need a specific version

[mkuf]

Adding a linter seems like a good idea.

---

If one wants to override the Image for a specific service, the existing docker-compose.override.yaml may be used. Do you have a specific usecase in mind, where this is not working?

[hz61p1]

@mkuf It works, but this way allows you to override at a higher level and not to copy-paste, but also to set the desired versions in one file (.env) or at the command line level

[mkuf]

This is introducing additional complexity for the end user by adding functionality which is already present via another configuration file.
I understand where you're coming from, but as the number of users directly benefiting from this change is expected to be very low, I'd rather not merge this as is.

If you're limiting this PR to the linting workflow, I'm happy to merge this.

[hz61p1]

@mkuf I've updated the pr

[mkuf]

Merged, thanks!