Revert "First steps into pytz deprecation"

This reverts commit e4e7d50659.

src/pretix/base/models/items.py

@@ -39,9 +39,9 @@ from collections import Counter, OrderedDict
 from datetime import date, datetime, time
 from decimal import Decimal, DecimalException
 from typing import Tuple
-from zoneinfo import ZoneInfo
 
 import dateutil.parser
+import pytz
 from django.conf import settings
 from django.core.exceptions import ValidationError
 from django.core.validators import MinValueValidator, RegexValidator
@@ -1474,7 +1474,7 @@ class Question(LoggedModel):
             try:
                 dt = dateutil.parser.parse(answer)
                 if is_naive(dt):
-                    dt = make_aware(dt, ZoneInfo(self.event.settings.timezone))
+                    dt = make_aware(dt, pytz.timezone(self.event.settings.timezone))
             except:
                 raise ValidationError(_('Invalid datetime input.'))
             else: