avoid mutable default constructor values

src/pipecat/services/fish/tts.py

@@ -52,7 +52,7 @@ class FishAudioTTSService(InterruptibleTTSService):
         model: str,  # This is the reference_id
         output_format: FishAudioOutputFormat = "pcm",
         sample_rate: Optional[int] = None,
-        params: InputParams = InputParams(),
+        params: Optional[InputParams] = None,
         **kwargs,
     ):
         super().__init__(
@@ -62,6 +62,8 @@ class FishAudioTTSService(InterruptibleTTSService):
             **kwargs,
         )
 
+        params = params or FishAudioTTSService.InputParams()
+
         self._api_key = api_key
         self._base_url = "wss://api.fish.audio/v1/tts/live"
         self._websocket = None