RFE: use `zoneinfo` instead of `pytz`

[kloczek]

Switch to standard zoneinfo module.
Below may help pydantic/pydantic-core@fd262933

[deronnax]

I can do that. @mvantellingen would you accept a PR doing this change ?

[mvantellingen]

That would be great!

[deronnax]

I did the work in #1442