(fix): Filter withdrawals by username on admin endpoint

Controllers/api/v2/admin/rewards/withdrawals.php

@@ -25,8 +25,8 @@ class withdrawals implements Interfaces\Api, Interfaces\ApiAdminPam
 
         $userGuid = null;
 
-        if ($_GET['username']) {
-            $userGuid = (new User(strtolower($_GET['username'])))->guid;
+        if ($_GET['user']) {
+            $userGuid = (new User(strtolower($_GET['user'])))->guid;
         }
 
         $status = $_GET['status'] ?? null;