Update README.md CosyVoice2 vllm Usage

First change env and then pip libs

Author: UncleLLD

README.md

@@ -170,8 +170,8 @@ Notice that `vllm==v0.9.0` has a lot of specific requirements, for example `torc
 
 ``` sh
 conda create -n cosyvoice_vllm --clone cosyvoice
-pip install vllm==v0.9.0 -i https://mirrors.aliyun.com/pypi/simple/ --trusted-host=mirrors.aliyun.com
 conda activate cosyvoice_vllm
+pip install vllm==v0.9.0 -i https://mirrors.aliyun.com/pypi/simple/ --trusted-host=mirrors.aliyun.com
 python vllm_example.py
 ```