message: use deserialize helper for validator_id
diff: @@ -3,7 +3,6 @@ use std::vec::Vec;
  use casper_types::{bytesrepr, Key, ProtocolVersion, PublicKey, U512};
  use crate::shared::{newtypes::Blake2bHash, TypeMismatch};
  -use casper_types::bytesrepr::FromBytes;
  use core::fmt;
  use std::fmt::Display;
  use uint::static_assertions::_core::fmt::Formatter;
  @@ -64,7 +63,7 @@ impl StepRequest {
  pub fn slashed_validators(&self) -> Result<Vec<PublicKey>, bytesrepr::Error> {
  let mut ret = vec![];
  for slash_item in &self.slash_items {
  - let (public_key, _) = PublicKey::from_bytes(slash_item.validator_id.as_slice())?;
  + let public_key: PublicKey = bytesrepr::deserialize(slash_item.validator_id.clone())?;
  ret.push(public_key);
  }
  Ok(ret)
  