Add request retry

[ErikBjare]

We've had some CI issue where OpenAI sometimes spuriously closes the connection. In these cases we should retry the request at least once.

I worked around the CI thing by adding a retry action for the step in the workflow, but with a retry in gptme itself, it should become unnecessary.

[nslieske]

I saw plenty of these capacity issues over the past few days. It was easy to ignore and move along. They are ongoing, but hard to understand if it's a bug expected functionality. On a side, but related note, often the app just quits, leaving me with no way to troubleshoot and provide any real feedback. Perhaps when the app just quits, it pushes a summary of why it quit and then optionally restarts itself.