RFE: use zoneinfo instead of pytz

[kloczek]

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

[tkloczko@pers-jacek flask-babel-4.0.0]$ grep -r pytz
README.md:[babel][] and [pytz][] modules.
README.md:[pytz]: https://pypi.python.org/pypi/pytz/
docs/index.rst:any Flask application with the help of `babel`_, `pytz`_ and its own copy of
docs/index.rst:.. _pytz: https://pythonhosted.org/pytz/
flask_babel/__init__.py:from pytz import timezone, UTC
flask_babel/__init__.py:        `pytz.timezone` object.
flask_babel/__init__.py:    a `pytz.timezone` object.  This returns `None` if used outside a request.
pyproject.toml:pytz = ">=2022.7"

[TkTech]

zoneinfo is only available in Python 3.9+ and we currently support versions before that. When 3.8 hits EOL in 2024-10, we'll switch.

[kloczek]

All what you wrote is 100% accurate.
In dropped in RFE commit you have example how to handle that.

[andreymal]

There is backports.zoneinfo (and Django 4.2 uses it, for example)