fix(utxo-lib): remove trailing comma
fix(utxo-lib): remove trailing comma

This is not es5 compatible, and since there is not (yet) any
precompilation step for utxo-lib, terser encounters an error on this
syntax.

Ticket: BG-31305

BitGo/BitGoJS,BitGo/BitGoJS,BitGo/BitGoJS,BitGo/BitGoJS