Bump python-version used by docs workflow to 3.12

.github/workflows/docs.yml

@@ -13,7 +13,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: "3.8"
+          python-version: "3.12"
       - name: Install dependencies
         run: |
           python -m pip install -U pip install wheel setuptools