Salt: fix incorrect dependency for boussole

This didn't get updated when boussole was split out to its own
virtualenv, and was still being linked to the pip installs from the
application succeeding.

salt/salt/boussole.sls

@@ -29,7 +29,7 @@ boussole.service:
   service.running:
     - enable: True
     - require:
-      - pip: pip-installs
+      - cmd: boussole-pip-installs
 
 create-css-directory:
   file.directory: