mirage/serializers/application: Remove redundant keyForCollection() override

This is the default serialization for the ActiveModelSerializer

Author: Turbo87

mirage/serializers/application.js

@@ -1,11 +1,3 @@
 import { ActiveModelSerializer } from 'ember-cli-mirage';
 
-export default ActiveModelSerializer.extend({
-    keyForCollection(modelName) {
-        if (modelName === 'version-download') {
-            return 'version_downloads';
-        }
-
-        return ActiveModelSerializer.prototype.keyForCollection.apply(this, arguments);
-    }
-});
+export default ActiveModelSerializer;