Added whitespace following styleCI [skip ci]

Author: vuongxuongminh

tests/Message/IncomingRequestTest.php

@@ -60,4 +60,5 @@ public function testIncoming()
         $this->assertEquals(11, $data['vnp_SecureHash']);
         $this->assertEquals(12, $data['vnp_SecureHashType']);
     }
-}
+    
+}

tests/Message/PurchaseRequestTest.php

@@ -73,4 +73,5 @@ public function testGetData()
         $this->assertTrue(isset($data['vnp_SecureHash']));
         $this->assertFalse(isset($data['vnp_HashSecret']));
     }
-}
+
+}

tests/Message/PurchaseResponseTest.php

@@ -42,4 +42,5 @@ public function testPurchase()
         $this->assertEquals('123', $response->vnp_TxnRef);
         $this->assertEquals('123', $response->vnpTxnRef);
     }
-}
+
+}

tests/Message/QueryTransactionRequestTest.php

@@ -67,4 +67,5 @@ public function testGetData()
         $this->assertTrue(isset($data['vnp_SecureHash']));
         $this->assertFalse(isset($data['vnp_HashSecret']));
     }
-}
+
+}

tests/Message/RefundRequestTest.php

@@ -70,4 +70,5 @@ public function testGetData()
         $this->assertTrue(isset($data['vnp_SecureHash']));
         $this->assertFalse(isset($data['vnp_HashSecret']));
     }
-}
+
+}

tests/Message/SignatureResponseTest.php

@@ -53,4 +53,5 @@ public function testIncoming()
         $this->assertEquals('12996460', $response->getTransactionReference());
         $this->assertEquals('00', $response->getCode());
     }
-}
+
+}