Fix deprecation warnings in dependencies

[hugovk]

Description

There's lots of deprecation warnings at https://github.com/python/pythondotorg/actions/runs/22328504402/job/64605126832#step:9:13

Most are from Django, but these are from dependencies:

/opt/hostedtoolcache/Python/3.12.6/x64/lib/python3.12/site-packages/dateutil/tz/tz.py:37: DeprecationWarning: datetime.datetime.utcfromtimestamp() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.datetime.fromtimestamp(timestamp, datetime.UTC).
  EPOCH = datetime.datetime.utcfromtimestamp(0)
/opt/hostedtoolcache/Python/3.12.6/x64/lib/python3.12/site-packages/pytz/tzinfo.py:27: DeprecationWarning: datetime.datetime.utcfromtimestamp() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.datetime.fromtimestamp(timestamp, datetime.UTC).
  _epoch = datetime.utcfromtimestamp(0)

The first is from dateutil. We can fix by upgrading to the latest version.

The second is from pytz. We only use pytz.UTC from here, and can instead replace it with the stdlib's datetime.UTC, and ditch the dependency altogether.

And run uv lock to update uv.lock.

[Copilot]

Pull request overview

This pull request fixes deprecation warnings from dependencies by upgrading python-dateutil and replacing the pytz library with Python's standard library datetime.UTC. The changes address warnings about datetime.datetime.utcfromtimestamp() being deprecated in favor of timezone-aware datetime objects.

Changes:

• Upgraded python-dateutil from 2.8.2 to 2.9.0.post0 to fix dateutil deprecation warnings
• Removed pytz dependency and replaced all usages with datetime.UTC (Python 3.11+ standard library)
• Updated uv.lock with dependency upgrades including django-tastypie, factory-boy, faker, model-bakery, and other transitive dependencies

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
pyproject.toml	Removed pytz dependency, upgraded python-dateutil to 2.9.0.post0
apps/events/utils.py	Replaced pytz imports and pytz.UTC references with datetime.UTC
uv.lock	Updated lock file with new dependency versions after running uv lock

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[JacobCoffee]

thanks!