chore: add missing openai.fm models to voice Literal

[hironow]

• [x] I understand that this repository is auto-generated and my pull request may not be merged

Changes being requested

• Update the voice Literal definition in the dependency library to include two missing model names ( ballad , verse ) from openai.fm.
• This change is necessary to support the new voice options and to resolve the test failures in the dependent project ( openai/openai-agents-python ).
• A synchronized update of the dependency and the consuming project is required for full compatibility.

Additional context & links

Related PR: https://github.com/openai/openai-agents-python/pull/269