qt.qpa.plugin: Could not load the Qt platform plugin "windows" in "" even though it was found.
学习北京理工的《Python科学计算三维可视化》时，运行示例代码出现如下错误：
qt.qpa.plugin: Could not load the Qt platform plugin "windows" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: direct2d, minimal, offscreen, windows.