DEV: migrate routes to the new @action pattern (#126)

assets/javascripts/discourse/routes/admin-plugins-house-ads-index.js.es6

@@ -1,9 +1,9 @@
 import DiscourseRoute from "discourse/routes/discourse";
+import { action } from "@ember/object";
 
 export default DiscourseRoute.extend({
-  actions: {
+  @action
   moreSettings() {
     this.transitionTo("adminSiteSettingsCategory", "ad_plugin");
   },
-  },
 });