Bug: style guideline and formatting inconsistencies

[davidlapsleyio]

Describe the bug

Running "make format" identifies coding style violations. 3 files are affected:

• src/agents/voice/model.py
• src/agents/models/openai_chatcompletions.py
• tests/test_extra_headers.py

Debug information

• Agents SDK version: v0.0.13
• Python version: Python 3.13.3

Repro steps

1. Check out the commit in question:

   git checkout aa197e1e1431ec8ad381575d0ea5a9667a9c2fcb
   make format
   git status

2. You will see the three files have had unnecessary spacing and lines removed.