環境是mac機！
下載官方python包正常，第一次運行pip3，版本為：
pip 19.2.3
但是會出現警告提示：
WARNING: You are using pip version 19.2.3, however version 20.3.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
進行升級：
pip3 install --upgrade pip --user
安裝可以完成，但是出現新的錯誤，也就是標題提到的那個：
WARNING: pip is being invoked by an old script wrapper. This will fail in a future version of pip.
Please see https://github.com/pypa/pip/issues/5599 for advice on fixing the underlying issue.
To avoid this problem you can invoke Python with '-m pip' instead of running pip directly.
解決辦法是：
比如原來使用pip3 list(能正常工作，但是會報錯)，改為：
python3 -m pip list
即可！！！