You are using pip version 10.0.1, however version 20.0.2 is available.

不要用 python -m pip install --upgrade pip
使用这个 python -m pip install -U --force-reinstall pip

(venv) D:\IPProxyPool>python -m pip install -U --force-reinstall pip
Looking in indexes: https://pypi.tuna.tsinghua.edu.cn/simple
Collecting pip
  Downloading https://pypi.tuna.tsinghua.edu.cn/packages/54/0c/d01aa759fdc501a58f431eb594a17495f15b88da142ce14b5845662c13f3/pip-20.0.2
-py2.py3-none-any.whl (1.4 MB)
     |████████████████████████████████| 1.4 MB 1.1 MB/s
Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 20.0.2
    Uninstalling pip-20.0.2:
      Successfully uninstalled pip-20.0.2
Successfully installed pip-20.0.2