www/py-dj40-django-timezone-field: Fix regression with newer pytz

• Backport a PR which fixes the "ZoneInfoNotFoundError" exception whe populating and comparing timezones against pytz which don't yet exist in zoneinfo.

MFH: 2022Q3
(cherry picked from commit 66b2b44abd3491418e2ca1efc64796375745cfc8)