refactor: remove unnecessary tobytes() calls when retrieving file content

--bug=1058211 --user=王孝刚 【应用】高级编排-应用对话，图片理解、语音转文本模型执行报错 https://www.tapd.cn/62980211/s/1725144

Author: wxg0103

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

@@ -30,7 +30,7 @@ def process_audio_item(audio_item, model):
             # 根据file_name 吧文件转成mp3格式
             file_format = file.file_name.split('.')[-1]
             with tempfile.NamedTemporaryFile(delete=False, suffix=f'.{file_format}') as temp_file:
-                temp_file.write(file.get_bytes().tobytes())
+                temp_file.write(file.get_bytes())
                 temp_file_path = temp_file.name
             with tempfile.NamedTemporaryFile(delete=False, suffix='.mp3') as temp_amr_file:
                 temp_mp3_path = temp_amr_file.name