Columbus Day 2023 markets are open, for the expiry date of Oct 9, 2023. How are the holidays maintained? Any workarounds?

Trying to find the last mkt day before the expiration date for options. Running the below code with expiry of Oct 9,2023 is returning Oct 6,2023, expecting Oct 9,2023.

tradingCalendar = self.TradingCalendar

list(tradingCalendar.GetDaysByType(TradingDayType.BusinessDay, expiry - timedelta(days = 20), expiry))[-1].Date