Add Chat and Whisper functionality

[benhalpern]

Is your feature request related to a problem? Please describe.
OpenAI added new functionality:

https://platform.openai.com/docs/guides/chat
https://platform.openai.com/docs/guides/speech-to-text

Describe the solution you'd like
Let's get this library up-to-date :)

[alexrudall]

ChatGPT is released in version v3.4, give it a try ;)

PRs welcomed for Whisper

[merefield]

@alexrudall I just released a "chat bot" adaptor for Discourse based forums using your API a few hours ago: https://github.com/merefield/discourse-chatbot which works with text-davinci-003 by default.

I really appreciate you implementing the changes for the new API so fast, I'll try to make some time to convert it to gpt-3.5-turbo in the next few days.

Thanks to you and everyone working on the Ruby API 👍

[merefield]

And that's DONE FYI ... and working really nicely, thank you!

[Clemalfroy]

ChatGPT is released in version v3.4, give it a try ;)

PRs welcomed for Whisper

#200

[alexrudall]

Whisper added in v3.5, big thanks @Clemalfroy!