Fix ChatClient.audio_to_text files keyword to make it work (#26317)

Co-authored-by: crazywoola <100913391+crazywoola@users.noreply.github.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

sdks/python-client/dify_client/client.py

         data = {"user": user}
         return self._send_request("DELETE", f"/conversations/{conversation_id}", data)
 
-    def audio_to_text(self, audio_file: dict, user: str):
+    def audio_to_text(self, audio_file: IO[bytes] | tuple, user: str):
         data = {"user": user}
-        files = {"audio_file": audio_file}
+        files = {"file": audio_file}
         return self._send_request_with_files("POST", "/audio-to-text", data, files)