Update admin.py

Author: ericholscher

readthedocs/sphinx_domains/admin.py

@@ -5,7 +5,7 @@
 
 
 class SphinxDomainAdmin(admin.ModelAdmin):
-    list_filter = ('type')
+    list_filter = ('type',)
     raw_id_fields = ('project', 'version')
     search_fields = ('doc_name', 'name')