message: fix(server): prevent to output Transfer-encoding when server upgrade
diff: @@ -214,6 +214,7 @@ impl Server<()> {
  match head.subject {
  // TODO: support for 1xx codes needs improvement everywhere
  // would be 100...199 => false
  + StatusCode::SwitchingProtocols |
  StatusCode::NoContent |
  StatusCode::NotModified => false,
  _ => true,
  