message: Fix: `purser-software` message verification
diff: /* @flow */
  -import { bigNumberify } from 'ethers/utils';
  -import { Wallet as EthersWallet } from 'ethers/wallet';
  +import {
  + bigNumberify,
  + verifyMessage as verifyEthersMessage,
  +} from 'ethers/utils';
  import {
  transactionObjectValidator,
  @@ -154,7 +156,7 @@ export const verifyMessage = async ({
  signatureMessage,
  );
  try {
  - const recoveredAddress: string = EthersWallet.verifyMessage(
  + const recoveredAddress: string = verifyEthersMessage(
  message,
  signature,
  );
  