message: Change `Responder` debug format to include type names
diff: //! effects to turn them into events should also be kept brief.
  use std::{
  + any::type_name,
  fmt::{self, Debug, Display, Formatter},
  future::Future,
  time::{Duration, Instant},
  @@ -82,7 +83,12 @@ impl<T, Ev> Responder<T, Ev> {
  impl<T, Ev> Debug for Responder<T, Ev> {
  fn fmt(&self, formatter: &mut Formatter<'_>) -> fmt::Result {
  - write!(formatter, "responder")
  + write!(
  + formatter,
  + "Responder<{}->{}>",
  + type_name::<T>(),
  + type_name::<Effect<Ev>>()
  + )
  }
  }
  