chore: found the places where no minting voucher should be done.

Author: nemo83

cardano/onchain/validators/spending_transfer_module.ak

@@ -264,6 +264,7 @@ fn handler_callback(
         packet.source_channel,
         data.denom,
       ) {
+        // TODO: check no minting voucher here
         let voucher_prefix_len =
           transfer_coin.get_denom_prefix(
             packet.source_port,
@@ -794,6 +795,7 @@ fn validate_refund_packet_token(
     packet.source_channel,
     data.denom,
   ) {
+    // TODO: check no minting voucher here
     expect Some(escrowed_token_unit) =
       string_utils.hex_string_to_bytes(data.denom)
     trace @"spend_transfer_module: demon convert to token unit valid"