update VectorClientExecutor python api, test=doc

res is dict not response, fixed

demos/speech_server/README.md

@@ -301,7 +301,7 @@ wget -c https://paddlespeech.bj.bcebos.com/vector/audio/123456789.wav
       server_ip="127.0.0.1",
       port=8090,
       task="spk")
-  print(res.json())
+  print(res)
   ```
 
   Output:
@@ -360,7 +360,7 @@ wget -c https://paddlespeech.bj.bcebos.com/vector/audio/123456789.wav
       server_ip="127.0.0.1",
       port=8090,
       task="score")
-  print(res.json())
+  print(res)
   ```
 
   Output: