Changed Stream to DuplexStreamInterface in Response::__construct

Https does not work without this:

Catchable fatal error: Argument 1 passed to React\HttpClient\Response::__construct() must be an instance of React\Stream\Stream, instance of React\SocketClient\SecureStream given, called in /Users/matt/PhpstormProjects/httpsClient/vendor/react/http-client/src/Request.php on line 239 and defined in /Users/matt/PhpstormProjects/httpsClient/vendor/react/http-client/src/Response.php on line 28