Cardano Updates

Support all Shelley-compatible transaction bodies

  Since transaction binary formats in Cardano are always forward-compatible, if we attempt to deserialise a Shelley transaction as an Alonzo transaction, it just works. Thus, it is sufficient to deserialise transactions to the latest era only.
  This change does however a little more as it makes sure that the compiler will raise a proper error when the latest era changes. This ensures that, on next updates, this part of the code won't be forgotten. For example, trying to deserialise a transaction as a Mary transaction, we now get:

  ```
  • Couldn't match type ‘AlonzoEra crypto’ with ‘MaryEra crypto’

    Expected type: GenTx (LatestEra (CardanoEras crypto)) -> GenTx (CardanoBlock crypto)
      Actual type: GenTx (ShelleyBlock (MaryEra crypto))  -> GenTx (CardanoBlock crypto)
  ```

  These are quite generic function belonging to a prelude, so no needs to overload the body of functions with needless where clauses.