PyQt5安装后报错：This application failed to start because no Qt platform plugin could be initialized.
PyQt5安装后运行报错：This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
原因：没有添加环境变量
解决：添加系统环境变量
变量名：QT_QPA_PLATFORM_PLUGIN_PATH
变量值：pyqt的plugins文件夹路径