參考
pyparsing 無法卸載導致安裝 matplotlib 出錯
解決 Cannot uninstall 'pyparsing' 問題
在安裝 pydot 時遇到依賴 pyparsing 無法更新問題：
Successfully built pyparsing
Installing collected packages: pyparsing
Found existing installation: pyparsing 2.0.1
Cannot uninstall 'pyparsing'. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.
解決方法是手動重裝最新版 pyparsing：
sudo pip install -I pyparsing==2.2.0