Add Django 4.0 compatibility

Author: codingjoe

django_select2/forms.py

@@ -52,8 +52,8 @@
 from itertools import chain
 from pickle import PicklingError  # nosec
 
+import django
 from django import forms
-from django.contrib.admin.utils import lookup_needs_distinct
 from django.contrib.admin.widgets import SELECT2_TRANSLATIONS
 from django.core import signing
 from django.db.models import Q
@@ -64,6 +64,11 @@
 from .cache import cache
 from .conf import settings
 
+if django.VERSION < (4, 0):
+    from django.contrib.admin.utils import lookup_needs_distinct as lookup_spawns_duplicates
+else:
+    from django.contrib.admin.utils import lookup_spawns_duplicates
+
 
 class Select2Mixin:
     """
@@ -407,15 +412,15 @@ def filter_queryset(self, request, term, queryset=None, **dependent_fields):
             or_queries = [Q(**{orm_lookup: term}) for orm_lookup in search_fields]
             select |= reduce(operator.or_, or_queries)
             use_distinct |= any(
-                lookup_needs_distinct(queryset.model._meta, search_spec)
+                lookup_spawns_duplicates(queryset.model._meta, search_spec)
                 for search_spec in search_fields
             )
 
         if dependent_fields:
             select &= Q(**dependent_fields)
 
         use_distinct |= any(
-            lookup_needs_distinct(queryset.model._meta, search_spec)
+            lookup_spawns_duplicates(queryset.model._meta, search_spec)
             for search_spec in dependent_fields.keys()
         )