fix: upgrade faster-whisper to 1.2.1 to resolve av build failure

faster-whisper 1.0.0 depends on av==11.* which has no prebuilt wheels
and fails to compile. Version 1.2.1 uses av 12+ with prebuilt wheels.
Also removed unnecessary FFmpeg dev libraries from Dockerfile.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/services/voice-service/Dockerfile

@@ -6,14 +6,6 @@ WORKDIR /app
 RUN apt-get update && apt-get install -y \
     ffmpeg \
     libsndfile1 \
-    build-essential \
-    pkg-config \
-    libavformat-dev \
-    libavcodec-dev \
-    libavdevice-dev \
-    libavutil-dev \
-    libswscale-dev \
-    libswresample-dev \
     && rm -rf /var/lib/apt/lists/*
 
 COPY requirements.txt .

packages/services/voice-service/requirements.txt

@@ -1,7 +1,7 @@
 fastapi==0.110.0
 uvicorn==0.29.0
 pipecat-ai==0.0.30
-faster-whisper==1.0.0
+faster-whisper==1.2.1
 kokoro==0.3.0
 silero-vad==5.1
 twilio==9.0.0