Integration Tests Panic

[TheAdamSmith]

Describe the bug
Integration tests do not run and exit with a panic

    api_integration_test.go:86: error, status code: 404, message: The model `ada` has been deprecated, learn more here: https://platform.openai.com/docs/deprecations [
CreateCompletionStream returned error]
--- FAIL: TestAPI (2.53s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
        panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x6a7cf4]

based on the error it is because the models the integration tests are using are deprecated. So we should be able to just upgrade them to the closest compatible model.

To Reproduce
Run the integration tests as detailed in the readme

Expected behavior
Test should run successfully