Use dateutil.tz over pytz ?

[pllim]

Brought up at Astropy ALOHA 2024. cc @ejeschke @eteq

https://dateutil.readthedocs.io/en/stable/tz.html

[pllim]

Might have to drop some really old Python versions, but not sure.

[eteq]

Just looked and it seems like pytz is only needed in python version < 3.9, and I think that means it's not a big issue. There would need to be a change from pytz.timezone to zoninfo.ZoneInfo.

[pllim]

So should we bump minversions and be done with it?