docker: Cleanup every hour

docker/init.sls

@@ -94,7 +94,7 @@ docker-volume-root:
 docker-cleanup:
   cron.present:
     - name: 'docker system prune --force --all{% if 'gitlab-ci' in salt['pillar.get']('roles', []) %} --volumes{% endif %}'
-    - hour: '8'
+    - hour: '*'
     - minute: '42'
     - require:
       - pkg: docker