Fix doc push error (#83)

Author: maximthomas

.github/workflows/deploy.yml

@@ -103,6 +103,8 @@ jobs:
           rm -rf ${REPO_NAME_LC}/modules
           cp -R ../${SITE_DOC_FOLDER}/target/asciidoc/antora/modules ../doc.openidentityplatform.org/${REPO_NAME_LC}
           git add -A
-          git commit -a -m "upload ${{github.event.repository.name}} docs after deploy ${{ github.sha }}"
-          git push --force
-          
+          if ! git diff-index --quiet HEAD; then
+            echo "committing changes to the docs repository"   
+            git commit -a -m "upload ${{github.event.repository.name}} docs after deploy ${{ github.sha }}"
+            git push --force
+          fi