python修改镜像源
https://www.cnblogs.com/wooya/p/6371511.html
1、在pycharm中修改
https://blog.csdn.net/IAMoldpan/article/details/78544598
2、在命令中临时修改
pip3 install -i https://pypi.tuna.tsinghua.edu.cn/simple pillow
原文：https://www.cnblogs.com/andy9468/p/9982154.html