Adding superevent category to API filter params

gracedb/superevents/api/views.py

@@ -55,7 +55,7 @@ class SupereventViewSet(SafeCreateMixin, viewsets.ModelViewSet):
     filter_backends = (SupereventSearchFilter, SupereventOrderingFilter,)
     ordering_fields = ('created', 't_0', 't_start', 't_end',
         'preferred_event__id', 't_0_date', 'is_gw', 'base_date_number',
-        'gw_date_number')
+        'gw_date_number', 'category')
 
     def get_serializer_class(self):
         """Select a different serializer for updates"""