Function create_final_cet_sig 

pub fn create_final_cet_sig(
    pubkey: String,
    num_digits: u8,
    oracle_signatures: String,
    cet_value_wildcard: String,
    cet_sighash: String,
    adaptor_signature: String,
) -> PyResult<String>

Perform final signing of a CET, decrypt a signature when outcome signatures are available. Return the decrypted signature.