base_url not included when request to gpt in SingleTableGPTModel

[jalr4ever]

Description

I updated the way to obtain the OpenAI client in sdgx/models/LLM/single_table/gpt.py (for easier testing) and ensured that it can use the user-injected base_url parameter in requests.

Motivation and Context

It's a bug fix that ensures base_url included when the client makes a request to GPT.

How has this been tested?

I tested it by test_singletable_gpt_model_openapi_setting()

Types of changes

• Maintenance (no change in code, maintain the project's CI, docs, etc.)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[MooooCat]

Looks good to me!

In the future, we will also need to refactor the LLM interface used in SDG to accommodate more types of model vendors and add features such as prompt management.

[MooooCat]

lgtm