tests bug fix + JET quality & type stability check

[algunion]

The completion test was broken. The main reason for that was that the model used was retrieved by r.response["data"][begin]["id"], which is not guaranteed always to return a model that is compatible with the completion endpoint (these days it returns the whisper-1 model). The test completion test is using text-ada-001 model now.

Other changes:

• created a separate test file for chat completion: despite the naming similarity, the /v1/chat/completions has nothing to do with /v1/completions. If a test fails, we need to be able to differentiate between the two easily.
• added JET code quality test - this check will work as a helpful additional QA layer

[algunion]

Just wanted to trigger the tests again - after adding the OPENAI_API_KEY variable to the repo.

[algunion]

The CI/test still fails to use the env key. Local tests passed.

If a different configuration is needed and you can point me out to that, please let me know, and I'll add that.

This is my current settings:
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[roryl23]

I'm not entirely sure what the problem is with CI tests in GitHub actions, I'll look at it this weekend