Add on-unlabeled.yml

[koppor]

This includes m7kvqbe1/github-action-move-issues#7 in our workflows.

Draft because of m7kvqbe1/github-action-move-issues#4 -- we do not want to "flood" our projects with non-curated issues.

Mandatory checks

• I own the copyright of the code submitted and I licence it under the MIT license
• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

[github-actions]

The build of this PR is available at https://builds.jabref.org/pull/11970/merge.

[github-actions]

The build of this PR is available at https://builds.jabref.org/pull/11970/merge.

[koppor]

I will merge to be able to give feedback to the author of the action.

[github-actions]

The build for this PR is no longer available. Please visit https://builds.jabref.org/main/ for the latest build.