Add repeatable argument to the directive

…  schema representation.

src/Language/GraphQL/Validate.hs

@@ -482,4 +482,4 @@ directive context rule (Full.Directive directiveName arguments' _) =
             $ Validation.schema context
      in arguments rule argumentTypes arguments'
   where
-    directiveArguments (Schema.Directive _ _ argumentTypes) = argumentTypes
+    directiveArguments (Schema.Directive _ argumentTypes _ _) = argumentTypes