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/plugins/badges/__init__.py

@@ -1,5 +1,5 @@
 from django.apps import AppConfig
-from django.utils.translation import ugettext, ugettext_lazy as _
+from django.utils.translation import gettext, gettext_lazy as _
 
 from pretix import __version__ as version
 
@@ -21,7 +21,7 @@ class BadgesApp(AppConfig):
     def installed(self, event):
         if not event.badge_layouts.exists():
             event.badge_layouts.create(
-                name=ugettext('Default'),
+                name=gettext('Default'),
                 default=True,
             )
 

src/pretix/plugins/badges/exporters.py

@@ -11,7 +11,7 @@ from django.core.files import File
 from django.core.files.storage import default_storage
 from django.db.models import Exists, OuterRef
 from django.db.models.functions import Coalesce
-from django.utils.translation import ugettext as _, ugettext_lazy
+from django.utils.translation import gettext as _, gettext_lazy
 from jsonfallback.functions import JSONExtract
 from reportlab.lib import pagesizes
 from reportlab.lib.units import mm
@@ -38,7 +38,7 @@ def _renderer(event, layout):
 
 OPTIONS = OrderedDict([
     ('one', {
-        'name': ugettext_lazy('One badge per page'),
+        'name': gettext_lazy('One badge per page'),
         'cols': 1,
         'rows': 1,
         'margins': [0, 0, 0, 0],
@@ -46,7 +46,7 @@ OPTIONS = OrderedDict([
         'pagesize': None,
     }),
     ('a4_a6l', {
-        'name': ugettext_lazy('4 landscape A6 pages on one A4 page'),
+        'name': gettext_lazy('4 landscape A6 pages on one A4 page'),
         'cols': 2,
         'rows': 2,
         'margins': [0 * mm, 0 * mm, 0 * mm, 0 * mm],
@@ -54,7 +54,7 @@ OPTIONS = OrderedDict([
         'pagesize': pagesizes.landscape(pagesizes.A4),
     }),
     ('a4_a6p', {
-        'name': ugettext_lazy('4 portrait A6 pages on one A4 page'),
+        'name': gettext_lazy('4 portrait A6 pages on one A4 page'),
         'cols': 2,
         'rows': 2,
         'margins': [0 * mm, 0 * mm, 0 * mm, 0 * mm],
@@ -62,7 +62,7 @@ OPTIONS = OrderedDict([
         'pagesize': pagesizes.portrait(pagesizes.A4),
     }),
     ('a4_a7l', {
-        'name': ugettext_lazy('8 landscape A7 pages on one A4 page'),
+        'name': gettext_lazy('8 landscape A7 pages on one A4 page'),
         'cols': 2,
         'rows': 4,
         'margins': [0 * mm, 0 * mm, 0 * mm, 0 * mm],
@@ -70,7 +70,7 @@ OPTIONS = OrderedDict([
         'pagesize': pagesizes.portrait(pagesizes.A4),
     }),
     ('a4_a7p', {
-        'name': ugettext_lazy('8 portrait A7 pages on one A4 page'),
+        'name': gettext_lazy('8 portrait A7 pages on one A4 page'),
         'cols': 4,
         'rows': 2,
         'margins': [0 * mm, 0 * mm, 0 * mm, 0 * mm],

src/pretix/plugins/badges/forms.py

@@ -1,7 +1,7 @@
 from django import forms
 from django.forms import Field
 from django.forms.models import ModelChoiceIterator
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 
 from pretix.plugins.badges.models import BadgeItem, BadgeLayout
 

src/pretix/plugins/badges/models.py

@@ -2,7 +2,7 @@ import string
 
 from django.db import models
 from django.utils.crypto import get_random_string
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 
 from pretix.base.models import LoggedModel
 

src/pretix/plugins/badges/signals.py

@@ -6,7 +6,7 @@ from django.dispatch import receiver
 from django.template.loader import get_template
 from django.urls import resolve, reverse
 from django.utils.html import escape
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 
 from pretix.base.models import Event, Order
 from pretix.base.signals import (

src/pretix/plugins/badges/views.py

@@ -13,7 +13,7 @@ from django.templatetags.static import static
 from django.urls import reverse
 from django.utils.functional import cached_property
 from django.utils.timezone import now
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 from django.views import View
 from django.views.generic import CreateView, DeleteView, DetailView, ListView
 from reportlab.lib import pagesizes