[FEAT] Add gpqa diamond

[shruthan]

📌 Description

Adds GPQA Diamond Audio.

Has 155 of 198 speakable samples converted to speech for evaluation at ServiceNow-AI/gpqa_audio.

On parallel text run, GPT 4o mini scores 39 (reported 40.8 at https://openai.com/index/gpt-4o-mini-advancing-cost-efficient-intelligence/)

On audio:
GPT 4o mini: 28.9 +- 0.86 (5 runs)
Voxtral Small: 27.1
Phi 4 Multimodal Instruct: 22.58

🛠️ Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality including new tasks)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactor / Code cleanup
• Maintenance / Chore / Task
• Other (please describe):

✅ How Has This Been Tested?

• Unit tests
• Integration tests
• Manual testing

Test Results / Screenshots (if applicable):

📸 Screenshots / Demos

📋 Checklist

• Code follows project style guidelines
• Tests have been added/updated (if applicable)
• Documentation has been updated (if applicable)
• Linked relevant issue(s)
• Self-reviewed my code

🙌 Additional Notes

[akshaykalkunte]

LGTM

[shruthan]

With some more filtering of samples for audio quality, the dataset now has 147 samples.
Scores are largely similar except Voxtral Small that now scores 29.93