Use structured outputs for speaker selection in `SelectorGroupChat`

[Ethan0456]

Why are these changes needed?

To improve the reliability of speaker selection in SelectorGroupChat by using structured outputs.

Related issue number

Closes #5970

Checks

• [x] I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://github.com/microsoft/autogen/blob/main/CONTRIBUTING.md to build and test documentation locally.
• [x] I've added tests (if relevant) corresponding to the changes introduced in this PR.
• [x] I've made sure all auto checks have passed.

[Ethan0456]

Hi @ekzhu,

I’m encountering the following mypy error:

src/autogen_agentchat/teams/_group_chat/_selector_group_chat.py:183: error: Second
argument of Enum() must be string, tuple, list or dict literal for mypy to determine Enum members [misc]

This error occurs on the line:

AgentName = Enum("AgentName", agent_name_map)

Since we need to dynamically create the Enum, I’m using # type: ignore to bypass the error.

References:

• Mypy Issue #5317
• Stack Overflow Discussion

[ekzhu]

Thanks for the change. We will run some benchmarks on our side and see.

cc @afourney