Install babel in CI for locale display name generation

Author: sylvestre

.github/workflows/website.yml

@@ -49,6 +49,7 @@ jobs:
     - name: Install system deps
       run: |
         sudo apt install libacl1-dev libselinux1-dev libsystemd-dev
+        pip install babel
 
     - name: Install necessary tools (mdbook and mdbook-toc)
       uses: taiki-e/install-action@v2