适用于Ubuntu 20.04的opencv-3.3.1资源

适用于Ubuntu 20.04的opencv-3.3.1资源；经过我的修改，解决了error: ‘CODEC_FLAG_GLOBAL_HEADER’ was not declared in this scope、error: ‘AVFMT_RAWPICTURE’ was not declared in this scope、error: invalid conversion from ‘const char*’ to ‘char*’ [-fpermissive] 856 | char* str = PyString_AsString(obj);等错误。