Add openai 4o Model

[lrauhockey]

Is your feature request related to a problem? Please describe.

Open AI released a new model gtp-4o, so want to add this to the list of models in the drop down and usable by Devika

Describe the solution you'd like

To see the OpenAI GPT-4o Model in the dropdown of models, and to execute using that model

Describe alternatives you've considered

Not sure if there is a complex solution to this just added one line to llm.py Line 41: ("GPT-4o", "gpt-4o"),

Additional context

No other context - but adding the new model, it is available I tested it with the code change locally