Fix invalid XML when UPS returns "Too Many Requests" error

Author: vernard

app/code/core/Mage/Usa/Model/Shipping/Carrier/Ups.php

@@ -848,6 +848,7 @@ protected function _parseXmlResponse($xmlResponse)
         $costArr = [];
         $priceArr = [];
         if (strlen(trim($xmlResponse)) > 0) {
+            $xmlResponse = str_replace('<?xmlversion="1.0"?>', '<?xml version="1.0"?>', $xmlResponse);
             $xml = new Varien_Simplexml_Config();
             $xml->loadString($xmlResponse);
             $arr = $xml->getXpath('//RatingServiceSelectionResponse/Response/ResponseStatusCode/text()');