message: remove generic serialisation of the Hash
diff: @@ -166,7 +166,6 @@ impl<T: Clone, A: SigningAlgorithm> Clone for Signed<T, A> {
  }
  /// Hash that is used as an address of the various components.
  -#[cfg_attr(feature = "generic-serialization", derive(serde_derive::Serialize))]
  #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
  pub struct Hash(crypto::Blake2b256);
  impl Hash {
  