docs: remove unneeded @depreacted in ResponseInterface::getStatusCode()

See https://github.com/php-fig/http-message/blob/master/src/ResponseInterface.php#L30

Author: kenjis

system/HTTP/ResponseInterface.php

@@ -110,8 +110,6 @@ interface ResponseInterface extends MessageInterface
      * to understand and satisfy the request.
      *
      * @return int Status code.
-     *
-     * @deprecated To be replaced by the PSR-7 version (compatible)
      */
     public function getStatusCode(): int;