Adding support for OpenAI GPT5 models

[knotmyrealname]

I'm looking to work with GPT-5 instead of the currently supported GPT-4 models as they cheaper and more powerful. I would not say that this is a complete integration - it'll need more work before I'm satisfied.

GPT-5 only supports a temperature of 1 - I could not find an elegant way of integrating this into the repository without adding a whole bunch of code. There are a few options I identified, and I can push those if desired

• add a helper function to test the api routes before execution (also saves time, should probably already be a thing)
• directly add gpt-5 temperature checks to the LLM.setup() function (hacky but takes the least effort)
• override temperature values for gpt-5 classes (will require a redefined functions in a new GPT-5 class)

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