Fixed Signature for this request is not valid by rxcod9

Author: Jon Eyrick

php-binance-api.php

@@ -882,7 +882,9 @@ private function httpRequest(string $url, string $method = "GET", array $params
             $query = http_build_query($params, '', '&');
             $signature = hash_hmac('sha256', $query, $this->api_secret);
 			if ($method === "POST") {
-				$endpoint = $base . $url . '?'  . 'signature=' . $signature;
+				$endpoint = $base . $url;
+				$params['signature'] = $signature; // signature needs to be inside BODY
+				$query = http_build_query($params, '', '&'); // rebuilding query
 			} else
 				$endpoint = $base . $url . '?' . $query . '&signature=' . $signature;
             curl_setopt($curl, CURLOPT_URL, $endpoint);