Update to Django 4.0

[brianjbuck]

Currently RestFramework does not support Django 4.0 deprecation of pytz:

/opt/hostedtoolcache/Python/3.8.12/x64/lib/python3.8/site-packages/rest_framework/fields.py:32: in <module>
    from pytz.exceptions import InvalidTimeError
E   ModuleNotFoundError: No module named 'pytz'

Update to Django 4.0 when Restframework is released.

[Zagrebelin]

Hello,

Dec, 13 DRF released 3.13 version with a django 4.0 support
encode/django-rest-framework#8178