Returns the next available nonce for `address`.

def parity_discover_next_available_nonce(
        web3: Web3,
        address: AddressHex,
) -> Nonce:
    """Returns the next available nonce for `address`."""
    next_nonce_encoded = web3.manager.request_blocking('parity_nextNonce', [address])
    return Nonce(int(next_nonce_encoded, 16))