Update Azure OpenAI API to 2024-02-15-preview (#1692)

On April 2, 2024 the following API preview releases will be retired and will stop accepting API requests:

2023-03-15-preview
2023-06-01-preview
2023-07-01-preview
2023-08-01-preview

To avoid service disruptions, update to use the latest version 2024-02-15-preview.

https://review.learn.microsoft.com/en-us/azure/ai-services/openai/api-version-deprecation