🚀 feat(constants.py): add new OpenAI chat models and update existing ones

Added new OpenAI chat models to the CHAT_OPENAI_MODELS list to improve the quality of the chatbot responses. The new models are "gpt-3.5-turbo-0613", "gpt-3.5-turbo-16k-0613", "gpt-4-0613", and "gpt-4-32k-0613". The existing models "gpt-3.5-turbo" and "gpt-4-32k" were also updated to their latest versions.