you are using pip version 19.(you are using pip 19.2.3)

pip install 报如下错误：且
pip install --upgrade pip 没有效果

You are using pip version 8.1.1, however version 22.0.4 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

下载get-pip.py

wget https://bootstrap.pypa.io/pip/2.7/get-pip.py

2.执行get-pip.py

sudo python get-pip.py