old_contents: from django.contrib import admin
  
  from models import Maintenance, MaintenanceFilter
  
  class MaintenanceFilterInline(admin.StackedInline):
      model = MaintenanceFilter
  
  class MaintenanceAdmin(admin.ModelAdmin):
      list_display = ('start_time', 'end_time', 'enabled')
      list_filter = ('start_time', 'end_time', 'enabled')
      list_editable = ('enabled',)
      inlines = (MaintenanceFilterInline,)
      
  admin.site.register(Maintenance, MaintenanceAdmin)
new_contents: from django.contrib import admin
  
  from models import Maintenance, MaintenanceFilter
  
  class MaintenanceFilterInline(admin.TabularInline):
      model = MaintenanceFilter
  
  class MaintenanceAdmin(admin.ModelAdmin):
      list_display = ('start_time', 'end_time', 'enabled')
      list_filter = ('start_time', 'end_time', 'enabled')
      list_editable = ('enabled',)
      inlines = (MaintenanceFilterInline,)
      
  admin.site.register(Maintenance, MaintenanceAdmin)
subject: Update maintenance/admin.py