drop to python 3.6 to match official build job

Author: tyeth

.github/workflows/docs.yml

@@ -13,7 +13,7 @@ on:
       build-python-version:
         description: Python version used for docs build
         type: string
-        default: 3.11
+        default: 3.6
 
 jobs:
   build_pages:
@@ -22,7 +22,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5
         with:
-          python-version: ${{ inputs.build-python-version || '3.11' }}
+          python-version: ${{ inputs.build-python-version || '3.6' }}
           cache: "pip"
       - name: Install the project dependencies
         run: |