nixos/unifi: restart service on package update

Currently the service doesn't detect if on of the packages is updated
and doesn't restart.

By manually adding a trigger we make sure the service restarts if any of
the involved packages update.

nixos/modules/services/networking/unifi.nix

@@ -162,6 +162,8 @@ in
       unitConfig.RequiresMountsFor = stateDir;
       # This a HACK to fix missing dependencies of dynamic libs extracted from jars
       environment.LD_LIBRARY_PATH = with pkgs.stdenv; "${cc.cc.lib}/lib";
+      # Make sure package upgrades trigger a service restart
+      restartTriggers = [ cfg.unifiPackage cfg.mongodbPackage ];
 
       serviceConfig = {
         Type = "simple";