Add ffmpeg and torch to CI for Whisper speech tests

- Install ffmpeg via apt-get for audio processing
- Install CPU-only torch for Whisper model inference
- Install openai-whisper explicitly before package

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: jeremymanning

.github/workflows/tests.yml

@@ -22,10 +22,17 @@ jobs:
       with:
         python-version: ${{ matrix.python-version }}
 
+    - name: Install system dependencies
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y ffmpeg
+
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
         pip install pytest pytest-cov
+        pip install torch --index-url https://download.pytorch.org/whl/cpu
+        pip install openai-whisper
         pip install -e .
 
     - name: Run tests