account_client sub_account_update() doesn't support mode 2

[EUA]

The API support mode 2, which is required to me, to get available balance every time. https://huobiapi.github.io/docs/spot/v1/en/#subscribe-account-change

But it's not possible to set mode parameter by hand using mode="2" argument because it discarded by function:

        if str(mode) == AccountBalanceMode.TOTAL:
            mode = AccountBalanceMode.TOTAL
        else:
            mode = AccountBalanceMode.BALANCE
        

        params = {
            "mode" : mode,
        }