making changes to tx builder model

[logicalmechanism]

Adding a signature to a conway era transaction causes a called Result::unwrap()on anErr value: CorruptedTxBytes error.

let signed_tx_cbor = tx
    // called `Result::unwrap()` on an `Err` value: CorruptedTxBytes
    .add_signature(witness_public_key, witness_vector)
    .unwrap()
    .tx_bytes;

This error comes from line 685 in model.rs of the txbuilder.

If you change the babbage call into a conway call then it does not throw the error.

This PR changes the babbage to conway on all the things. Also, it adjusts the witness building as pushing to a set is not possible and requires coverting back to a vector then back to an empty set.

This PR passes all current tests. There is no open issue on this topic as it brought up in discord.

[logicalmechanism]

I also commented out a debug statement that clutters the terminal screen.