fix: STT default parameter

Author: zhanweizhang7

apps/application/flow/step_node/speech_to_text_step_node/impl/base_speech_to_text_node.py

@@ -23,7 +23,7 @@ def save_context(self, details, workflow_manage):
 
     def execute(self, stt_model_id, audio, model_params_setting=None, **kwargs) -> NodeResult:
         workspace_id = self.workflow_manage.get_body().get('workspace_id')
-        stt_model = get_model_instance_by_model_workspace_id(stt_model_id, workspace_id, **model_params_setting)
+        stt_model = get_model_instance_by_model_workspace_id(stt_model_id, workspace_id, **(model_params_setting or {}))
         audio_list = audio
         self.context['audio_list'] = audio