message: Change `Responder` display format to be easier to read and not include length effect type
diff: @@ -94,7 +94,7 @@ impl<T, Ev> Debug for Responder<T, Ev> {
  impl<T, Ev> Display for Responder<T, Ev> {
  fn fmt(&self, formatter: &mut Formatter<'_>) -> fmt::Result {
  - Debug::fmt(self, formatter)
  + write!(formatter, "responder({})", type_name::<T>(),)
  }
  }
  