Fix Boussole writing the initial CSS compile as root.

ansible/roles/boussole/tasks/main.yml

@@ -35,6 +35,7 @@
   register: compiled_css_files
 
 - name: Run boussole manually if no compiled CSS exists yet
+  become_user: "{{ app_username }}"
   command:
     chdir: "{{ app_dir }}"
     cmd: "{{ boussole_venv_dir }}/bin/boussole compile --backend=yaml --config=boussole.yaml"