ConsumeStatus.CONSUME_SUCCESS is deprecated？

I could not find the ```ConsumeStatus.CONSUME_SUCCESS ``` follow in Readme.md

So , I find the below and use it callback return

```
from rocketmq.ffi import _CConsumeStatus

def callback(msg):
...
return _CConsumeStatus.CONSUME_SUCCESS

```

python version 3.7

pip version
```
root@2340c37e8721:/workspace# pip list | grep rocket
rocketmq 0.4.4
rocketmq-client-python 2.0.0
```
cpp version
2.0.0

Start with Readme.md and the callback example described in the issue, then inspect how rocketmq.ffi._CConsumeStatus is exposed in the Python client. Confirm whether ConsumeStatus.CONSUME_SUCCESS is supported or deprecated for the listed versions, and document the correct callback return value and usage.

Escrito por el modelo de indexación a partir del texto del issue.