Rebuild the library with Windows, GTK+ 2.x or Cocoa support
windows系统：
出现该错误是因为opencv-python和opencv-contrib-python包版本不兼容导致的，
解决方法：
pip install opencv-contrib-python
如果不行，再用下面的方法试试：
先将原有的opencv-python和opencv-contrib-python包卸载。
重新在终端中运行（更新重新安装opencv-python包）
pip install opencv-python --upgrade
再重新安装opencv-contrib-python包
pip install opencv-contrib-python