Revert "First steps into pytz deprecation"

This reverts commit e4e7d50659.

src/pretix/base/services/checkin.py

@@ -32,7 +32,7 @@
 # distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations under the License.
 import os
-from datetime import datetime, timedelta, timezone
+from datetime import datetime, timedelta
 from functools import partial, reduce
 
 import dateutil
@@ -439,7 +439,7 @@ class SQLLogic:
 
         if operator == 'buildTime':
             if values[0] == "custom":
-                return Value(dateutil.parser.parse(values[1]).astimezone(timezone.utc))
+                return Value(dateutil.parser.parse(values[1]).astimezone(pytz.UTC))
             elif values[0] == "customtime":
                 parsed = dateutil.parser.parse(values[1])
                 return Value(now().astimezone(self.list.event.timezone).replace(
@@ -447,7 +447,7 @@ class SQLLogic:
                     minute=parsed.minute,
                     second=parsed.second,
                     microsecond=parsed.microsecond,
-                ).astimezone(timezone.utc))
+                ).astimezone(pytz.UTC))
             elif values[0] == 'date_from':
                 return Coalesce(
                     F('subevent__date_from'),
@@ -475,7 +475,7 @@ class SQLLogic:
             return int(values[1])
         elif operator == 'var':
             if values[0] == 'now':
-                return Value(now().astimezone(timezone.utc))
+                return Value(now().astimezone(pytz.UTC))
             elif values[0] == 'now_isoweekday':
                 return Value(now().astimezone(self.list.event.timezone).isoweekday())
             elif values[0] == 'product':

src/pretix/base/services/mail.py

@@ -45,8 +45,8 @@ from email.mime.image import MIMEImage
 from email.utils import formataddr
 from typing import Any, Dict, List, Sequence, Union
 from urllib.parse import urljoin, urlparse
-from zoneinfo import ZoneInfo
 
+import pytz
 import requests
 from bs4 import BeautifulSoup
 from celery import chain
@@ -218,11 +218,11 @@ def mail(email: Union[str, Sequence[str]], subject: str, template: Union[str, La
         if event:
             timezone = event.timezone
         elif user:
-            timezone = ZoneInfo(user.timezone)
+            timezone = pytz.timezone(user.timezone)
         elif organizer:
             timezone = organizer.timezone
         else:
-            timezone = ZoneInfo(settings.TIME_ZONE)
+            timezone = pytz.timezone(settings.TIME_ZONE)
 
         if settings_holder:
             if settings_holder.settings.mail_bcc: