message: refactor(core): use `.flat()` in backupKeyRecovery
  Begone lodash
  Issue:
diff: @@ -258,7 +258,7 @@ export async function backupKeyRecovery(
  RootWalletKeys.defaultPrefix,
  ]);
  - const unspents: WalletUnspent[] = _.flatten(
  + const unspents: WalletUnspent[] = (
  await Promise.all(
  outputScripts.scriptTypes2Of3
  .filter(
  @@ -273,7 +273,7 @@ export async function backupKeyRecovery(
  [] as Promise<WalletUnspent[]>[]
  )
  )
  - );
  + ).flat();
  // Execute the queries and gather the unspents
  const totalInputAmount = unspents.reduce((sum, u) => sum + u.value, 0);
  