Add pytz to requirements

[jtpio]

pytz is currently being imported and used here:

github-activity/github_activity/github_activity.py

Line 21 in 7e3a545

import pytz

github-activity/github_activity/github_activity.py

Line 835 in 7e3a545

dt = datetime.datetime.now().astimezone(pytz.utc)

However currently it's not defined as part of the requirements.

And the next version of pandas will make pytz an optional dependency: https://pandas.pydata.org/docs/dev/whatsnew/v3.0.0.html#pytz-now-an-optional-dependency

[jtpio]

This was noticed in jupyter-releaser, which has a check to test pre-releases: jupyter-server/jupyter_releaser#625 (comment)

[bsipocz]

Thanks!

[bsipocz]

@choldgraf - interestingly CI was passing here, so I was happy that we can go ahead with the release straight away, however it's failing again on main. Is it still about hitting rate limit or something else? If just the rate limit I would still think we should tag a new release now as main is way better already than what's in the latest release.