Switch to openai.ChatCompletion.create

[hophanms]

Now with gpt-4-32k, would it make sense to switch to openai.ChatCompletion.create instead of openai.Completion.create API?

I know there is dependency on chatgpt-api but that library doesn't help on supporting multi-sessions in Teams chat anyways (e.g. I chat with the bot in Team channel vs. direct chat should be 2 separate prompt histories)

Thought?

[freistli]

If the model is gpt-4, we should use Chat Completion. Currently rootbot uses Completion for GPT3.5-turbo model and supports multiple sessions in Teams.