Fix changelog checker

[agraul]

What does this PR change?

Use get-changed-files action, it also works on merged pull requests. Before, $files_modified was empty on merged pull requests and the workflow failed. Also simplified the ruby script while I was at it.

GUI diff

No diff.

• DONE

Documentation

• No documentation needed: github actions only

• DONE

Test coverage

• No tests: github actions only

GitHub is a bit slow for me today, I want to do another manual test in my fork before ticking "done".

• DONE

Links

Couldn't find any issue.

• DONE

Changelogs

If you don't need a changelog check, please mark this checkbox:

• No changelog needed

Re-run a test

If you need to re-run a test, please mark the related checkbox, it will be unchecked automatically once it has re-run:

• Re-run test "changelog_test"
• Re-run test "backend_unittests_pgsql"
• Re-run test "java_pgsql_tests"
• Re-run test "schema_migration_test_oracle"
• Re-run test "schema_migration_test_pgsql"
• Re-run test "susemanager_unittests"
• Re-run test "javascript_lint"
• Re-run test "spacecmd_unittests"

[Etheryte]

Out of curiosity, does get-changed-files also work for the pull_request_target hook (as opposed to the pull_request one we have right now)? If it does, we could also fix the problem that right now the bot can't comment on PRs when needed due to permissions. This is something that I tried to fix in #4368 and reverted in #4374 exactly because of issues with getting the changed files list.

[agraul]

Out of curiosity, does get-changed-files also work for the pull_request_target hook (as opposed to the pull_request one we have right now)?

Yes, this one does:

This project is a fork of https://github.com/jitterbit/get-changed-files, which supports pull_request_target, allow to filter files using regular expressions and removes the ahead check.

https://github.com/jitterbit/get-changed-files seems unmaintained, the PR that adds pull_request_target support is open for close to a year now. Hence this uses Ana's fork.

If it does, we could also fix the problem that right now the bot can't comment on PRs when needed due to permissions. This is something that I tried to fix in #4368 and reverted in #4374 exactly because of issues with getting the changed files list.

I'll s/pull_request/pull_request_target/ in the workflow yaml

[Etheryte]

Nice, thanks a lot for looking into this as well, this looks very good. 👍

[cbosdo]

LGTM but I honestly have no clue about github actions... so not sure such a review is actually useful ;)