FIX: Group Requests loading was broken

We were referencing the wrong property, which meant the footer was
always being hidden and we were trying to load more requests when we'd
already loaded them all.

see:
https://meta.discourse.org/t/constant-loading-on-group-membership-request-tab/166284

app/assets/javascripts/discourse/app/controllers/group-requests.js

@@ -36,7 +36,7 @@ export default Controller.extend({
       return;
     }
 
-    if (!refresh && model.members.length >= model.user_count) {
+    if (!refresh && model.requesters.length >= model.user_count) {
       this.set("application.showFooter", true);
       return;
     }