Add Ultravox service (#1)

Adds support for using Ultravox Realtime as a speech-to-speech service.

Also removes the deprecated Ultravox speech-to-text vllm model integration to avoid confusion.

pyproject.toml

@@ -109,7 +109,7 @@ strands = [ "strands-agents>=1.9.1,<2" ]
 tavus=[]
 together = []
 tracing = [ "opentelemetry-sdk>=1.33.0", "opentelemetry-api>=1.33.0", "opentelemetry-instrumentation>=0.54b0" ]
-ultravox = [ "transformers>=4.48.0", "vllm>=0.9.0" ]
+ultravox = [ "pipecat-ai[websockets-base]" ]
 webrtc = [ "aiortc>=1.13.0,<2", "opencv-python>=4.11.0.86,<5" ]
 websocket = [ "pipecat-ai[websockets-base]", "fastapi>=0.115.6,<0.122.0" ]
 websockets-base = [ "websockets>=13.1,<16.0" ]