V2 batch operation cannot post attribute for custom pydantic object

[djs0109]

Describe the bug
V2 batch operation update( )cannot post attributes when using custom pydantic object (For example inherited from the ContextEntity/ContextEntityKeyValues)

To Fix
Add SerializeAsAny annotation to the entities. Otherwise update.model_dump() will only serialize the object based on the schema, i.e., the ContextEntity or ContextEntityKeyValues. Therefore, only predefined attribute will be serialized, such as id and type.

class Update(BaseModel):
    """
    Model for update action
    """

    action_type: Union[ActionType, str] = Field(
        alias="actionType",
        description="actionType, to specify the kind of update action to do: "
        "either append, appendStrict, update, delete, or replace. ",
    )
    entities: SerializeAsAny[List[Union[ContextEntity, ContextEntityKeyValues]]] = Field(
        description="an array of entities, each entity specified using the "
        "JSON entity representation format "
    )