Doc CD: Change python version when building

Author: GratienDSX

.github/workflows/ci-cd-mkdocs.yml

@@ -23,7 +23,7 @@
         - name: Install Python
           uses: actions/setup-python@v5
           with:
-            python-version: '3.x'
+            python-version: '3.11'
         - name: Install package with optional dependency 'doc'
           run: |
             python -m pip install --upgrade pip