Revert "First steps into pytz deprecation"

This reverts commit e4e7d50659.

src/tests/base/test_orders.py

@@ -22,9 +22,9 @@
 import json
 from datetime import datetime, timedelta
 from decimal import Decimal
-from zoneinfo import ZoneInfo
 
 import pytest
+import pytz
 from django.core import mail as djmail
 from django.db.models import F, Sum
 from django.test import TestCase
@@ -255,9 +255,9 @@ def test_expiry_last_relative_subevents(event):
 @pytest.mark.django_db
 def test_expiry_dst(event):
     event.settings.set('timezone', 'Europe/Berlin')
-    tz = ZoneInfo('Europe/Berlin')
-    utc = ZoneInfo('UTC')
-    today = datetime(2016, 10, 29, 12, 0, 0, tzinfo=tz).astimezone(utc)
+    tz = pytz.timezone('Europe/Berlin')
+    utc = pytz.timezone('UTC')
+    today = tz.localize(datetime(2016, 10, 29, 12, 0, 0)).astimezone(utc)
     order = _create_order(event, email='dummy@example.org', positions=[],
                           now_dt=today,
                           payment_requests=[{