[Bug] Fix Regex for identifying OpenAI models

[alexander-brady]

Addresses the issue with the model naming convention used by Azure's OpenAI API. It updates the regex pattern to accommodate Azure's distinct format for their 3.5 models, which differs from the OpenAI API's convention. The specific change involves recognizing gpt-35-turbo as opposed to gpt-3.5-turbo.

Additionally, the deployment path check has been changed to handle scenarios where pathlib.parts does not include the deployment path, ensuring more robust path validation during Azure deployments.

Closes #761

[Harsha-Nori]

Hi @alexander-brady and @riedgar-ms, we may want to just move away from the regex-based scheme altogether. To my knowledge, only the gpt-3.5-turbo-instruct line of models uses the legacy Completion interface anymore, so we can perhaps just assume that the model is a ChatCompletion model with a special case exception for the -instruct suffixed models. Thoughts?

EDIT: Upon a bit of investigation, it looks like it is specifically these three model families that leverage the legacy completion endpoints:

https://platform.openai.com/docs/models/model-endpoint-compatibility

gpt-3.5-turbo-instruct, babbage-002, davinci-002

And of these, I don't believe babbage or davinci get any type of meaningful traffic.

[alexander-brady]

I looked into it as well, and it seems that is the case for Azure. Per the docs, OpenAI recommends not using the GPT base models babbage or davinci, instead recommending GPT-3.5/GPT-4.

I've therefore updated my pull request to check for -instruct instead of regex matching for both Azure and OpenAI.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 62.54%. Comparing base (92afe33) to head (837053c).

Files	Patch %	Lines
guidance/models/_azure_openai.py	0.00%	5 Missing ⚠️
guidance/models/_openai.py	0.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #778      +/-   ##
==========================================
+ Coverage   55.38%   62.54%   +7.16%     
==========================================
  Files          55       55              
  Lines        4079     4074       -5     
==========================================
+ Hits         2259     2548     +289     
+ Misses       1820     1526     -294     

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[riedgar-ms]

I shall take this opportunity to bring up a point I've mentioned before: do we really want to try autodetecting model types like this at all?

We are creating something inherently fragile, just to extract a single bit of information (chat vs completion). In the code, this has also led to a rather interesting coding pattern involving mutually recursive constructors, and objects which change their types dynamically.

As things stand, we are making life very marginally easier for newcomers. However, when it breaks (and given that we do not control the names of the OpenAI models, breakage is inevitable) I fear that those same newcomers will be in a worse position.

[alexander-brady]

As a newcomer, not detecting my model as a chat model made me reconsider even using this framework, and I almost gave up on it altogether before deciding to take a closer look at the source code.

However, since the majority of OpenAI models use the chat API, I think it's reasonable to make the model automatically be set to chat mode, with a parameter to change this if necessary. Especially if there's an error message that pops up, telling users how to fix it simply by changing the parameter.

[riedgar-ms]

My thoughts are more tending towards renoving the AzureOpenAI class, and having users instantiate AzureOpenAIChat or AzureOpenAICompletion as appropriate (and adjusting the latter two classes to have properly named arguments, rather than *args, **kwargs).

[riedgar-ms]

Despite my thoughts about whether this is really something we want to be doing, this should fix our immediate issues. @Harsha-Nori ?