Qt5 is now end of life. The libcamera 'qcam' application has removed support for Qt5, and updated to Qt6. Update the python 'cam' application accordingly to Qt6. Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>