Update SpeechmaticsSTTService to use the python voice SDK

changelog/3225.changed.md

@@ -0,0 +1,15 @@
+- Updated `SpeechmaticsSTTService` to use new Python Voice SDK with improved VAD,
+  Smart Turn capabilities, and brings dramatic improvements to latency without
+  any impact on accuracy. Use the `turn_detection_mode` parameter to control the
+  endpointing of speech, with `TurnDetectionMode.EXTERNAL` (default),
+  `TurnDetectionMode.ADAPTIVE`, or `TurnDetectionMode.SMART_TURN`.
+  ```python
+    stt = SpeechmaticsSTTService(
+        api_key=os.getenv("SPEECHMATICS_API_KEY"),
+        params=SpeechmaticsSTTService.InputParams(
+            language=Language.EN,
+            turn_detection_mode=SpeechmaticsSTTService.TurnDetectionMode.ADAPTIVE,
+            speaker_active_format="<{speaker_id}>{text}</{speaker_id}>",
+        ),
+    )
+  ```