auto_tag_stable.yml: try tuning to trigger a RtD build

.github/workflows/auto_tag_stable.yml

@@ -37,5 +37,9 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
+          touch .dummy-file
+          git add .dummy-file
+          # Do that so that stable doesn't have the same git sha as the stable branch, so ReadTheDocs triggers a build
+          git commit -a -m "Add .dummy-file"
           git tag -f stable
           git push -f origin stable