Django 4 compatibility

pretix_public_registrations/__init__.py

-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 try:
     from pretix.base.plugins import PluginConfig
 except ImportError:

pretix_public_registrations/forms.py

 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
 
 

pretix_public_registrations/signals.py

 from django import forms
 from django.dispatch import receiver
 from django.template.loader import get_template
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 from django.urls import resolve, reverse
 from django_gravatar.helpers import get_gravatar_url
 from pretix.base.signals import event_copy_data