!151 modify pip source in readme.md

From: @lvmingfu
Reviewed-by: @gemini524,@jxlang910,@pkuliuliu
Signed-off-by: @jxlang910,@pkuliuliu

README.md

@@ -97,7 +97,7 @@ The architecture is shown as follow：
 #### Installation by pip
 
 ```bash
-pip install https://ms-release.obs.cn-north-4.myhuaweicloud.com/{version}/MindArmour/{arch}/mindarmour-{version}-cp37-cp37m-linux_{arch}.whl --trusted-host ms-release.obs.cn-north-4.myhuaweicloud.com -i https://mirrors.huaweicloud.com/repository/pypi/simple
+pip install https://ms-release.obs.cn-north-4.myhuaweicloud.com/{version}/MindArmour/{arch}/mindarmour-{version}-cp37-cp37m-linux_{arch}.whl --trusted-host ms-release.obs.cn-north-4.myhuaweicloud.com -i https://pypi.tuna.tsinghua.edu.cn/simple
 ```
 
 > - When the network is connected, dependency items are automatically downloaded during .whl package installation. (For details about other dependency items, see [setup.py](https://gitee.com/mindspore/mindarmour/blob/master/setup.py)). In other cases, you need to manually install dependency items.

README_CN.md

@@ -94,7 +94,7 @@ Fuzz Testing模块的架构图如下：
 #### pip安装
 
 ```bash
-pip install https://ms-release.obs.cn-north-4.myhuaweicloud.com/{version}/MindArmour/{arch}/mindarmour-{version}-cp37-cp37m-linux_{arch}.whl --trusted-host ms-release.obs.cn-north-4.myhuaweicloud.com -i https://mirrors.huaweicloud.com/repository/pypi/simple
+pip install https://ms-release.obs.cn-north-4.myhuaweicloud.com/{version}/MindArmour/{arch}/mindarmour-{version}-cp37-cp37m-linux_{arch}.whl --trusted-host ms-release.obs.cn-north-4.myhuaweicloud.com -i https://pypi.tuna.tsinghua.edu.cn/simple
 ```
 
 > - 在联网状态下，安装whl包时会自动下载MindArmour安装包的依赖项（依赖项详情参见[setup.py](https://gitee.com/mindspore/mindarmour/blob/master/setup.py)），其余情况需自行安装。