translation workflow: Add new *.po files in addition to updating new ones

[ci skip]

Author: tobbi

.github/workflows/translations.yml

@@ -52,5 +52,6 @@ jobs:
           git status
           git config --global user.email "[email protected]"
           git config --global user.name "SuperTux Bot"
+          git add *.po || true
           git commit -am "Update translations" || true
           git push https://git:[email protected]/SuperTux/supertux.git master