Improve tests

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/mobilizon_web/schema.ex

@@ -131,6 +131,7 @@ defmodule MobilizonWeb.Schema do
     import_fields(:event_queries)
     import_fields(:participant_queries)
     import_fields(:category_queries)
+    import_fields(:tag_queries)
   end
 
   @desc """