package/opencv3: bump version to 3.4.2

Updated license hash after copyright year update:
https://github.com/opencv/opencv/commit/e6ed853905744018d9d570fa49e3b9e33b3c6ea6#diff-9879d6db96fd29134fc802214163b95a



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>