fix: 批量修复所有 DjangoFilterBackend 导入错误

backend/apps/moderation/views.py

@@ -1,4 +1,5 @@
 from rest_framework import viewsets, permissions, status, filters
+from django_filters.rest_framework import DjangoFilterBackend
 from rest_framework.decorators import action
 from rest_framework.response import Response
 from django.db.models import Q
@@ -21,7 +22,7 @@ class ModeratorApplicationViewSet(viewsets.ModelViewSet):
     """ViewSet for ModeratorApplication model."""
 
     permission_classes = [permissions.IsAuthenticated]
-    filter_backends = [filters.SearchFilter, filters.OrderingFilter, filters.DjangoFilterBackend]
+    filter_backends = [filters.SearchFilter, filters.OrderingFilter, DjangoFilterBackend]
     search_fields = ['applicant__username', 'region__name']
     filterset_fields = ['status', 'rank', 'region']
     ordering_fields = ['created_at', 'deadline']