Added getName method to Gateway

Author: vuongxuongminh

src/Gateway.php

@@ -23,6 +23,14 @@ class Gateway extends AbstractGateway
     use Concerns\Parameters;
     use Concerns\ParametersNormalization;
 
+    /**
+     * {@inheritdoc}
+     */
+    public function getName(): string
+    {
+        return 'VNPay';
+    }
+
     /**
      * {@inheritdoc}
      */