Pin Python 3.11 in pythonpublish workflow (#852)

Author: emontnemery

.github/workflows/pythonpublish.yml

@@ -15,7 +15,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5.0.0
       with:
-        python-version: '3.x'
+        python-version: '3.11'
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip