Add o1-preview support (or how to hack it in)

[johannesCmayer]

Currently, I can't do

(gptel-make-openai "custom1" :models '("o1-preview") :key gptel-api-key)

The problem I am running into so far is that o1-preview does not support system messages yet. And it seems gptel always tries to send system messages. Could there be an option not to send a system message (or what is the option if it exists)?

Alternatively, how can I hack it so that it works? Some pointers would be helpful.

[karthink]

There is an open PR to allow disabling the system message, see #339.