fix quote

.idea/workspace.xml

@@ -71,7 +71,7 @@
       <option name="number" value="Default" />
       <option name="presentableId" value="Default" />
       <updated>1600830685900</updated>
-      <workItem from="1600830687029" duration="1452000" />
+      <workItem from="1600830687029" duration="2385000" />
     </task>
     <servers />
   </component>

src/DummyPayDriver.php

@@ -30,7 +30,7 @@ class DummyPayDriver implements PaymentGatewayDriver
     public function createPaymentURL(PayableEntity $payable, array $options = []): string
     {
         $order_id = $payable->getBillId();
-        return "$this->callback_url?'".http_build_query(compact('order_id'));
+        return "$this->callback_url?".http_build_query(compact('order_id'));
     }
 
     public function verifyGatewayReturn(Request $request): bool