fix vcode

src/RazerPayDriver.php

         $bill_desc = urlencode(preg_replace('/[^A-Z0-9,\-_]/i', '_', $detail));
         $amount = sprintf('%0.2f', $payable->getBillAmount());
         $currency = $payable->getBillCurrency();
-        $verify_code = md5($amount . $this->merchant_id . $payable->getBillId() . $this->verify_key);
+        $vcode = md5($amount . $this->merchant_id . $payable->getBillId() . $this->verify_key);
 
         $query = array_merge(
             compact(
                 'amount', 'orderid', 'bill_name', 'bill_email', 'bill_mobile',
-                'bill_desc', 'country', 'verify_code', 'currency'
+                'bill_desc', 'country', 'vcode', 'currency'
             ),
             Arr::only($this->config->get('payment.gateway.razerpay.options', []), ['channel', 'returnurl', 'callbackurl']),
             Arr::only($options, ['channel', 'returnurl', 'callbackurl'])