Update utils.py

[gyanendrarawat]

Issue #, if available: models like text-davinci-002 has been deprecated by OpenAI. For more info refer : stackoverflow.com/questions/77806389/openai-api-error-openai-error-invalidrequesterror-the-model-text-davinci-003

Description of changes:

try_cot _colab.ipynb file is using model 'text-davinci-002' which i changed to 'gpt-3.5-turbo-instruct'. More models inside util.py might be deprecated. So kindly fix this issue.

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