handling of api_base

[njbrake]

Would this work when running the integration test with huggingface/tgi
I noticed that it sets the api_base in the model args:

any-agent/tests/integration/frameworks/test_agent.py

Line 159 in 3dad3f6

model_args["api_base"] = os.environ["HF_ENDPOINT"]

and agent_config.api_base might be None.
If thats the case, we might need something like:

agent_config.api_base or cast(
            "str | None", model_args.get("api_base")
        )

Originally posted by @HareeshBahuleyan in #840 (comment)