XOL-2788 Address code review comment

Author: rushi

src/Message/CIMRefundRequest.php

@@ -51,7 +51,7 @@ public function send()
         $parameters = $this->getParameters();
 
         if (!$response->isSuccessful() && $this->voidIfRefundFails &&
-            intval($response->getResponseReasonCode()) === CIMResponse::ERROR_RESPONSE_CODE_CANNOT_ISSUE_CREDIT) {
+            $response->getResponseReasonCode() === CIMResponse::ERROR_RESPONSE_CODE_CANNOT_ISSUE_CREDIT) {
             // An attempt to a refund a transaction that was not settled. We can just void the entire transaction
             $voidRequest = new CIMVoidRequest($this->httpClient, $this->httpRequest);
             $voidRequest->initialize($parameters);

src/Message/CIMResponse.php

@@ -10,7 +10,7 @@ class CIMResponse extends CIMAbstractResponse
     /**
      * For Error codes: @see https://developer.authorize.net/api/reference/responseCodes.html
      */
-    const ERROR_RESPONSE_CODE_CANNOT_ISSUE_CREDIT = 54;
+    const ERROR_RESPONSE_CODE_CANNOT_ISSUE_CREDIT = '54';
 
     protected $xmlRootElement = 'createCustomerProfileTransactionResponse';