fetch gh-actions branch before building docs

.github/workflows/docs.yml

@@ -16,6 +16,9 @@ jobs:
         run: |
           git config user.name github-actions
           git config user.email [email protected]
+      - name: Fetch gh-actions branch
+        run: |
+          git fetch origin gh-pages --depth=1
       - uses: actions/setup-python@v5
         with:
           python-version: 3.x