message: add Display implementation for the satke pook id
diff: @@ -141,6 +141,11 @@ impl From<chain_crypto::Blake2b256> for StakePoolId {
  StakePoolId(hash.into())
  }
  }
  +impl std::fmt::Display for StakePoolId {
  + fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
  + std::fmt::Display::fmt(&self.0, f)
  + }
  +}
  #[cfg(test)]
  mod test {
  