message: use legacy module to get OldAddress
diff: //! Mockchain ledger. Ledger exists in order to update the
  //! current state and verify transactions.
  +use crate::legacy;
  use crate::transaction::*;
  use crate::value::*;
  use crate::{account, utxo};
  -use cardano::address::Addr as OldAddress;
  use chain_addr::{Address, Kind};
  use chain_core::property;
  @@ -18,7 +18,7 @@ use chain_core::property;
  #[derive(Clone)]
  pub struct Ledger {
  pub(crate) utxos: utxo::Ledger<Address>,
  - pub(crate) oldutxos: utxo::Ledger<OldAddress>,
  + pub(crate) oldutxos: utxo::Ledger<legacy::OldAddress>,
  pub(crate) accounts: account::Ledger,
  }
  