Fix static analysis error

Error message:
    ERROR: InvalidArrayOffset - ../src/Curl/Curl.php:2182:25 - Cannot
    access value on variable $response_header_array using a int<-1, max>
    offset, expecting int<0, max> (see https://psalm.dev/115)
            if (stripos($response_header_array[$i], 'HTTP/') === 0) {

Author: zachborboa

src/Curl/Curl.php

@@ -2178,7 +2178,7 @@ private function parseResponseHeaders($raw_response_headers)
         $response_header_array = explode("\r\n\r\n", $raw_response_headers);
         $response_header  = '';
         for ($i = count($response_header_array) - 1; $i >= 0; $i--) {
-            if (stripos($response_header_array[$i], 'HTTP/') === 0) {
+            if (isset($response_header_array[$i]) && stripos($response_header_array[$i], 'HTTP/') === 0) {
                 $response_header = $response_header_array[$i];
                 break;
             }