Move away from deprecated set-output in workflow

Author: pmai

.github/workflows/build-guides.yml

@@ -42,7 +42,7 @@ jobs:
     - name: extract branch name
       id: extract_branch
       shell: bash
-      run: echo "##[set-output name=branch;]$(echo ${GITHUB_REF#refs/heads/})"
+      run: echo "branch=$(echo ${GITHUB_REF#refs/heads/})" >> $GITHUB_OUTPUT
     - name: deploy
       if: github.ref == 'refs/heads/main' && github.event_name == 'push'
       uses: peaceiris/actions-gh-pages@v3.9.3