Fixed #31154 -- Added support for using enumeration types in templates.

Enumeration helpers are callables, so the template system tried to call
them with no arguments.

Thanks Rupert Baker for helping discover this.

django/db/models/enums.py

@@ -31,6 +31,7 @@ class ChoicesMeta(enum.EnumMeta):
         # that is passed in as "self" as the value to use when looking up the
         # label in the choices.
         cls.label = property(lambda self: cls._value2label_map_.get(self.value))
+        cls.do_not_call_in_templates = True
         return enum.unique(cls)
 
     def __contains__(cls, member):