【记录】pip升级安装报错：WARNING: You are using pip version 20.0.2, however version 20.2.3 is available.

报错：

解决方案：

python -m pip install --upgrade pip -i https://pypi.douban.com/simple

指定源安装很重要，就是这一段 -i https://pypi.douban.com/simple