ENH: Add 2024-02-09 Chinese New Year to XSHG

[herebebeasties]

XSHG is missing last Friday from its list, which was the beginning of the Chinese New Year celebrations - see http://english.sse.com.cn/start/trading/schedule/ for the canonical list of holidays for 2024. I've also checked no others are missing. 👍🏻

Workflow to modify an existing Exchange Calendar

• Modify calendar class as required.
• Modify the test resources file (e.g tests/resources/{Exchange MIC}.csv), either manually or by executing python etc/make_exchange_calendar_test_csv.py {Exchange MIC}.
• Check if any of the fixtures in tests/test_{Exchange MIC}_calendar.py need updating to reflect your changes.
• Add references to any new/modified holidays in exchange_calendars/exchange_calendar_{Exchange MIC}.py.

[maread99]

Thanks @herebebeasties!