Workflow "Generate & push translated files" doesn't respect selected branch

**Short description**: When triggering the [Work on main branch to pull new & updated translations from tf branch](https://github.com/AntennaPod/antennapod.github.io/actions/workflows/translation-updates-to-main-repo.yml) workflow while selecting any other branch than the default (master), changes still get committed to master (rather than selected branch).

**More info**:
* https://github.com/AntennaPod/antennapod.github.io/blob/master/.github/workflows/translation-updates-to-main-repo.yml
* https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/accessing-contextual-information-about-workflow-runs#:~:text=for%20GitHub%20Actions.-,github.ref,-string
* https://github.com/orgs/community/discussions/30794#discussioncomment-3475536
* https://www.baeldung.com/ops/github-actions-get-current-branch