fix how we pass data

Author: muayyad-alsadi

FirebaseNotifications.php

@@ -84,8 +84,7 @@ public function sendDataMessage($tokens = [], $data, $collapse_key=null, $delay_
     {
         $body = [
             'registration_ids' => $tokens,
-            'data' => $data
-        ];
+        ]+$data;
         if ($collapse_key) $body['collapse_key']=$collapse_key;
         if ($delay_while_idle!==null) $body['delay_while_idle']=$delay_while_idle;
         if ($other) $body+=$other;