We haven’t published a tutorial on how to make a voice sample sound like an AI, as there is no ‘one true way’ to make an AI voice; The ‘best’ method depends entirely on what you want AIs to sound like in your game’s setting.
That being said, there are numerous tutorials on how to imitate or replicate GladOS’ voice on YouTube: https://www.youtube.com/results?search_query=how+to+sound+like+glados