Apple Inc. plans to open Siri to outside artificial intelligence assistants, a major move aimed at bolstering the iPhone as an AI platform.The company is preparing to make the change as part of a Siri overhaul in its upcoming iOS 27 operating system update, according to people with knowledge of the matter. The assistant can already tap into ChatGPT through a partnership with OpenAI, but Apple will now allow competing services to do the same....