Can't subscribe to multiple symbols at the same time

[AustinOwens]

When trying to subscribe to more than one symbol, __unpack_event(...) has issues unpacking multiple symbols.

For example:

# Subscribing to symbols across different instrument types
symbols = ["SPY", "AAPL"]

subscription = tasty.market_data.subscribe(
    symbols=symbols,
    on_quote=print,
    on_candle=print,
    on_greeks=print,
)

# start streaming
subscription.open()

Will result in: