DEPS/TST: tzdata is optional, not required
- [ ] closes #47332  (Replace xxxx with the Github issue number)
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

OK, this works now. We should probably specify a minimum tzdata version too, though.

@jbrockmendel Do you have anything in mind? no idea, cc @pganssle ? seems fine, does this need backport? > We should probably specify a minimum tzdata version too, though.

My 2c is might as well have the min version be the latest available version since this is a new feature.

> does this need backport?

Don't think so since `ZoneInfo` support will be new for 1.5. > > does this need backport?
> 
> Don't think so since `ZoneInfo` support will be new for 1.5.

correct. the failures were only on nightlies (main). 1.4.x is passing tests (or was when I last run the build test which is running again now ready for release https://github.com/MacPython/pandas-wheels/pull/173)
 Zoneinfo is also kinda wonky, since it doesn't really need the tzdata package, just a copy of the IANA tz database. I'm not sure we have a way to check the version of the IANA tz database, though. > Zoneinfo is also kinda wonky, since it doesn't really need the tzdata package, just a copy of the IANA tz database. I'm not sure we have a way to check the version of the IANA tz database, though.

I don't think we should necessarily runtime check `tzdata` in pandas, but it would be good to state that the minimum version we test with `tzdata=2022.1` This is blocking #47442, so we should probably merge this now, and open an issue to discuss tzdata version, since there is not yet enough consensus on that. IMO setting `tzdata=2022.1` should be okay for now. OK, so I've updated this PR again. It's too difficult/costly to check the version of the system IANA tz db if present, so we're just going to specify a minimum version.

If tzdata is installed, though, the minimum version will be enforced through a warning, even if they have an up to date IANA tz db, since we would want to warn them of the mismatch. Hello @lithomas1! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:









There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2022-08-09 13:55:50 UTC I'm going to self merge this in a couple of days if no other comments, so we can get the Python 3.11 testing in. thanks @lithomas1 this is great