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/stripe/__init__.py

@@ -1,6 +1,6 @@
 from django.apps import AppConfig
 from django.utils.functional import cached_property
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 
 from pretix import __version__ as version
 

src/pretix/plugins/stripe/forms.py

@@ -1,5 +1,5 @@
 from django import forms
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 
 from pretix.base.forms import SettingsForm
 

src/pretix/plugins/stripe/payment.py

@@ -17,7 +17,7 @@ from django.urls import reverse
 from django.utils.crypto import get_random_string
 from django.utils.safestring import mark_safe
 from django.utils.timezone import now
-from django.utils.translation import pgettext, ugettext, ugettext_lazy as _
+from django.utils.translation import gettext, gettext_lazy as _, pgettext
 from django_countries import countries
 
 from pretix import __version__
@@ -882,7 +882,7 @@ class StripeGiropay(StripeMethod):
                     'code': payment.order.code
                 },
                 owner={
-                    'name': request.session.get('payment_stripe_giropay_account') or ugettext('unknown name')
+                    'name': request.session.get('payment_stripe_giropay_account') or gettext('unknown name')
                 },
                 statement_descriptor=self.statement_descriptor(payment, 35),
                 redirect={
@@ -1033,7 +1033,7 @@ class StripeBancontact(StripeMethod):
                     'code': payment.order.code
                 },
                 owner={
-                    'name': request.session.get('payment_stripe_bancontact_account') or ugettext('unknown name')
+                    'name': request.session.get('payment_stripe_bancontact_account') or gettext('unknown name')
                 },
                 statement_descriptor=self.statement_descriptor(payment, 35),
                 redirect={
@@ -1166,7 +1166,7 @@ class StripeEPS(StripeMethod):
                     'code': payment.order.code
                 },
                 owner={
-                    'name': request.session.get('payment_stripe_eps_account') or ugettext('unknown name')
+                    'name': request.session.get('payment_stripe_eps_account') or gettext('unknown name')
                 },
                 statement_descriptor=self.statement_descriptor(payment),
                 redirect={

src/pretix/plugins/stripe/signals.py

@@ -5,7 +5,7 @@ from django import forms
 from django.dispatch import receiver
 from django.template.loader import get_template
 from django.urls import resolve, reverse
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 
 from pretix.base.settings import settings_hierarkey
 from pretix.base.signals import (

src/pretix/plugins/stripe/views.py

@@ -12,7 +12,7 @@ from django.shortcuts import get_object_or_404, redirect, render
 from django.urls import reverse
 from django.utils.decorators import method_decorator
 from django.utils.functional import cached_property
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 from django.views import View
 from django.views.decorators.clickjacking import xframe_options_exempt
 from django.views.decorators.csrf import csrf_exempt