Export RetrieveBtcStatusV2 (#504)

# Motivation

It's convenient to be able to refer to this type.

# Changes

`export RetrieveBtcStatusV2`

# Tests

Used in an nns-dapp branch.

# Todos

- [ ] Add entry to changelog (if necessary).
not necessary

packages/ckbtc/src/index.ts

@@ -3,6 +3,7 @@ export type {
   PendingUtxo,
   RetrieveBtcOk,
   RetrieveBtcStatus,
+  RetrieveBtcStatusV2,
   Account as WithdrawalAccount,
 } from "../candid/minter";
 export * from "./enums/btc.enums";