CI: Update to Python 3.11 on "docs" workflow

Author: amotl

.github/workflows/docs.yml

@@ -34,7 +34,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: "3.10"
+          python-version: "3.11"
 
       - name: Build docs
         run: |