#104 fix deprecation ts

[onlsol]

#104 fix: replace deprecated Timestamp.utcnow() and 'd' frequency/timedelta

[ValueRaider]

The file ~/.cache/py-yfinance-cache/options.json (created by yfc_cache_manager.py) stores max_age values in deprecated format. If this file was created before the fix, it contains lowercase 'd' values which trigger warnings.

Try adding an upgrade function to yfc_upgrade, and call it in the init. You can see previous times I've fixed cache.

Don't upgrade options, instead convert d -> D internally.