Add support for new Github and OpeanAI formats

[tamir-alltrue-ai]

• I'm submitting a ...

  • bug report
  • feature request

• What is the current behavior?

detect-secrets does not catch github's personal access token format - only the old api key format.

It also doesn't catch OpenAI's new secret format

• If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem

• What is the expected behavior?

Should catch:

• Github PATs, like github_pat_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
• OpenAI secrets like sk-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

• What is the motivation / use case for changing the behavior?
  These are two important secret detectors and without it you the library is much less useful

• Please tell us about your environment:

  • detect-secrets Version: 1.5.0
  • Python Version: 3.11
  • OS Version: Mac os 14.4 (23E214)
  • File type (if applicable):