Add Serialized Type Name kwarg in Model Output (#10502)

* Update outputs.py

src/diffusers/utils/outputs.py

@@ -71,6 +71,7 @@ class BaseOutput(OrderedDict):
                     cls,
                     torch.utils._pytree._dict_flatten,
                     lambda values, context: cls(**torch.utils._pytree._dict_unflatten(values, context)),
+                    serialized_type_name=f"{cls.__module__}.{cls.__name__}",
                 )
 
     def __post_init__(self) -> None: