Upgrade to Django 3.0 and other dependencies (#1568)

* Upgrade Django to 3.0 and other dependencies to recent versions

* Fix otp version contsraint

* Remove six dependency

* Resolve some warnings

* Fix failing tests

* Update django-countries

* Resolve all RemovedInDjango31Warnings in test suite

* Run isort

* Fix import

* Update PostgreSQL version on travis

src/pretix/base/services/cart.py

@@ -9,7 +9,7 @@ from django.db import DatabaseError, transaction
 from django.db.models import Count, Exists, OuterRef, Q
 from django.dispatch import receiver
 from django.utils.timezone import make_aware, now
-from django.utils.translation import pgettext_lazy, ugettext as _
+from django.utils.translation import gettext as _, pgettext_lazy
 from django_scopes import scopes_disabled
 
 from pretix.base.channels import get_all_sales_channels
@@ -213,7 +213,7 @@ class CartManager:
                 has_variations=Count('variations'),
             ).filter(
                 id__in=[i for i in item_ids if i and i not in self._items_cache]
-            )
+            ).order_by()
         })
         self._variations_cache.update({
             v.pk: v
@@ -221,7 +221,7 @@ class CartManager:
                 'quotas'
             ).select_related('item', 'item__event').filter(
                 id__in=[i for i in variation_ids if i and i not in self._variations_cache]
-            )
+            ).order_by()
         })
 
     def _check_max_cart_size(self):

src/pretix/base/services/checkin.py

@@ -2,7 +2,7 @@ from django.db import transaction
 from django.db.models import Prefetch
 from django.dispatch import receiver
 from django.utils.timezone import now
-from django.utils.translation import ugettext as _
+from django.utils.translation import gettext as _
 
 from pretix.base.models import (
     Checkin, CheckinList, Order, OrderPosition, Question, QuestionOption,

src/pretix/base/services/export.py

@@ -2,7 +2,7 @@ from typing import Any, Dict
 
 from django.core.files.base import ContentFile
 from django.utils.timezone import override
-from django.utils.translation import ugettext
+from django.utils.translation import gettext
 
 from pretix.base.i18n import LazyLocaleException, language
 from pretix.base.models import CachedFile, Event, cachedfile_name
@@ -26,7 +26,7 @@ def export(event: Event, fileid: str, provider: str, form_data: Dict[str, Any])
                 d = ex.render(form_data)
                 if d is None:
                     raise ExportError(
-                        ugettext('Your export did not contain any data.')
+                        gettext('Your export did not contain any data.')
                     )
                 file.filename, file.type, data = d
                 file.file.save(cachedfile_name(file, file.filename), ContentFile(data))

src/pretix/base/services/invoices.py

@@ -15,7 +15,7 @@ from django.dispatch import receiver
 from django.utils import timezone
 from django.utils.formats import date_format
 from django.utils.timezone import now
-from django.utils.translation import pgettext, ugettext as _
+from django.utils.translation import gettext as _, pgettext
 from django_countries.fields import Country
 from django_scopes import scope, scopes_disabled
 from i18nfield.strings import LazyI18nString

src/pretix/base/services/mail.py

@@ -20,7 +20,7 @@ from django.core.mail import (
 )
 from django.core.mail.message import SafeMIMEText
 from django.template.loader import get_template
-from django.utils.translation import pgettext, ugettext as _
+from django.utils.translation import gettext as _, pgettext
 from django_scopes import scope, scopes_disabled
 from i18nfield.strings import LazyI18nString
 

src/pretix/base/services/orders.py

@@ -15,7 +15,7 @@ from django.db.transaction import get_connection
 from django.dispatch import receiver
 from django.utils.functional import cached_property
 from django.utils.timezone import make_aware, now
-from django.utils.translation import ugettext as _
+from django.utils.translation import gettext as _
 from django_scopes import scopes_disabled
 
 from pretix.api.models import OAuthApplication

src/pretix/base/services/seating.py

@@ -1,5 +1,5 @@
 from django.db.models import Count, Q
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 
 from pretix.base.i18n import LazyLocaleException
 from pretix.base.models import CartPosition, Seat
@@ -25,7 +25,7 @@ def validate_plan_change(event, subevent, plan):
             subevent=subevent,
         ).filter(
             Q(has_v=True) | Q(has_op=True)
-        ).values_list('seat_guid', flat=True)
+        ).values_list('seat_guid', flat=True).order_by()
     )
     new_seats = {
         ss.guid for ss in plan.iter_all_seats()
@@ -40,7 +40,7 @@ def generate_seats(event, subevent, plan, mapping):
     current_seats = {}
     for s in event.seats.select_related('product').annotate(
             has_op=Count('orderposition'), has_v=Count('vouchers')
-    ).filter(subevent=subevent):
+    ).filter(subevent=subevent).order_by():
         if s.seat_guid in current_seats:
             s.delete()  # Duplicates should not exist
         else:

src/pretix/base/services/shredder.py

@@ -8,7 +8,7 @@ from dateutil.parser import parse
 from django.conf import settings
 from django.utils.crypto import get_random_string
 from django.utils.timezone import now
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 
 from pretix.base.models import CachedFile, Event, cachedfile_name
 from pretix.base.services.tasks import ProfiledEventTask

src/pretix/base/services/stats.py

@@ -6,7 +6,7 @@ from django.db.models import (
     Case, Count, DateTimeField, F, Max, OuterRef, Subquery, Sum, Value, When,
 )
 from django.utils.timezone import make_aware
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 
 from pretix.base.models import Event, Item, ItemCategory, Order, OrderPosition
 from pretix.base.models.event import SubEvent

src/pretix/base/services/tickets.py

@@ -3,7 +3,7 @@ import os
 
 from django.core.files.base import ContentFile
 from django.utils.timezone import now
-from django.utils.translation import ugettext as _
+from django.utils.translation import gettext as _
 from django_scopes import scopes_disabled
 
 from pretix.base.i18n import language

src/pretix/base/services/update_check.py

@@ -5,7 +5,7 @@ from datetime import timedelta
 import requests
 from django.dispatch import receiver
 from django.utils.timezone import now
-from django.utils.translation import ugettext_lazy as _, ugettext_noop
+from django.utils.translation import gettext_lazy as _, gettext_noop
 from django_scopes import scopes_disabled
 from i18nfield.strings import LazyI18nString
 
@@ -91,7 +91,7 @@ def send_update_notification_email():
         gs.settings.update_check_email,
         _('pretix update available'),
         LazyI18nString.from_gettext(
-            ugettext_noop(
+            gettext_noop(
                 'Hi!\n\nAn update is available for pretix or for one of the plugins you installed in your '
                 'pretix installation. Please click on the following link for more information:\n\n {url} \n\n'
                 'You can always find information on the latest updates on the pretix.eu blog:\n\n'