Specify token override using a custom httpx client

[pamelafox]

Purpose

There was concern with the previous method that developers may forget to refresh the token before sending a request, so now we pass in a custom httpx client to the OpenAI constructor, and set the authorization header inside that client.

Does this introduce a breaking change?

[ ] Yes
[X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[X] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• Run locally
• Deploy, wait a few hours, confirm it still works