Add check for missing license headers

[mjwolf]

Add make check_license_headers as a test workflow step, in order to detect any yaml or py files without the required license header.

• Have you signed the contributor license agreement? y
• Have you followed the contributor guidelines? y
• For proposing substantial changes or additions to the schema, have you reviewed the RFC process? n/a
• If submitting code/script changes, have you verified all tests pass locally using make test? y
• If submitting schema/fields updates, have you generated new artifacts by running make and committed those changes? n/a
• Is your pull request against main? Unless there is a good reason otherwise, we prefer pull requests against main and will backport as needed. y
• Have you added an entry to the CHANGELOG.next.md? n/a

[stbischof]

https://github.com/marketplace/actions/license-eye-header

You may want to use this ci task

[stbischof]

@mjwolf

Would be also nice if you not just check for

Licensed to Elasticsearch B.V.

But also check fot the Apache License

If its okay, i can do a pr with the ci Plugin. This way we can see this an an extra check in the pr

[mjwolf]

@mjwolf

Would be also nice if you not just check for

Licensed to Elasticsearch B.V.

But also check fot the Apache License

If its okay, i can do a pr with the ci Plugin. This way we can see this an an extra check in the pr

Hi @stbischof, if you'd like to create another PR for this, I'd appreciate it

[github-actions]

Hi!

We just realized that we haven't looked into this PR in a while. We're
sorry!

We're labeling this PR as Stale to make it hit our filters and
make sure we get back to it as soon as possible. In the meantime, it'd
be extremely helpful if you could take a look at it as well and confirm its
relevance. A simple comment with a nice emoji will be enough :+1.

Thank you for your contribution!

[stbischof]

@stbischof still my task