Update faber

.github/workflows/test-ubuntu.yml

@@ -28,6 +28,10 @@ jobs:
     steps:
     - uses: actions/checkout@v5
 
+    - name: setup prerequisites
+      run: |
+        # Warning: this is not necessarily the same Python version as the one configured above !
+        python3 -m pip install -U faber --break-system-packages
     - name: build
       run: |
         ${{ matrix.python }} --version