feat!: remove automatic function calling from Models.generate_content, Models_generate_content_stream, AsyncModels.generate_content, and AsyncModels.generate_content_stream. Automatic Function Calling is only available in Chats.send_message, Chats.send_message_stream, AsyncChats.send_message, AsyncChats.send_message_stream.

feat!: remove automatic function calling from Models.generate_content, Models_generate_content_stream, AsyncModels.generate_content, and AsyncModels.generate_content_stream. Automatic Function Calling is only available in Chats.send_message, Chats.send_message_stream, AsyncChats.send_message, AsyncChats.send_message_stream. #557