[BugFix] openbb-yfinance - Fix Key Error From Change In Response From yf.download()

[deeleeramone]

1. Why?:

   • New behavior by yFinance appears to have changed the shape of the response from yf.download when there is only one symbol.
     • Results in a KeyError because it is expecting a flat table response.

2. What?:

    if len(tickers) == 1:
        data = data.get(symbol)

3. Impact:

   • Bug fix.
   • Drops the "capital_gains", "dividend", and "split_ratio" when the sum of the column is 0 (equivalent to empty)
   • yFinance version bump.

4. Testing Done:

   • obb.equity.price.historical("IWM", provider="yfinance")
   • obb.equity.price.historical("IWM,QQQ,AAPL", provider="yfinance", start_date="2019-01-01")