Merge pull request #4713 from shuujii/fix-argument-specs-to-Enumerable

Fix argument specs to `Enumerable`

src/enum.c

@@ -26,5 +26,5 @@ mrb_init_enumerable(mrb_state *mrb)
 {
   struct RClass *enumerable;
   enumerable = mrb_define_module(mrb, "Enumerable");  /* 15.3.2 */
-  mrb_define_module_function(mrb, enumerable, "__update_hash", enum_update_hash, MRB_ARGS_REQ(1));
+  mrb_define_module_function(mrb, enumerable, "__update_hash", enum_update_hash, MRB_ARGS_REQ(3));
 }