https://mirrors.tuna.tsinghua.edu.cn/help/pypi/
pip install pip -U
pip config set global.index-url https://pypi.tuna.tsinghua.edu.cn/simple
https://mirrors.tuna.tsinghua.edu.cn/help/pypi/
pip install pip -U
pip config set global.index-url https://pypi.tuna.tsinghua.edu.cn/simple