old_contents: from attachments.models import Attachment
  from django.contrib.contenttypes import generic
  
  
  class AttachmentInlines(generic.GenericStackedInline):
      model = Attachment
      extra = 1
new_contents: from attachments.models import Attachment
  from django.contrib.contenttypes import admin
  
  
  class AttachmentInlines(admin.GenericStackedInline):
      model = Attachment
      extra = 1
subject: Fix deprecated modules for content types