package/opencv3: bump to version 3.4.15

Update hash of LICENSE (update in year:
https://github.com/opencv/opencv/commit/4f9cb3871a5d6552ef25229c2f81d2e1531c7df9)

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/opencv3/opencv3.hash

@@ -1,3 +1,3 @@
 # Locally calculated
-sha256  70230049194ae03ed8bfaab6cd1388569aa1b5c482d8b50d3af1cd2ae5a0b95d  opencv3-3.4.13.tar.gz
-sha256  a5a7cf90fe5ac9763baad852cf69cf9d9b89bff934a679fdc5c8fcecaeba9a25  LICENSE
+sha256  b1e8470b18e9e793bf70b4ae051bbc9bf81fa45f8cbfee1e6c88858c90be8ff7  opencv3-3.4.15.tar.gz
+sha256  9076d3d934839a2f8e7bfe549abda6faea4751f1edd6e9460ff703559890ad5f  LICENSE

package/opencv3/opencv3.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-OPENCV3_VERSION = 3.4.13
+OPENCV3_VERSION = 3.4.15
 OPENCV3_SITE = $(call github,opencv,opencv,$(OPENCV3_VERSION))
 OPENCV3_INSTALL_STAGING = YES
 OPENCV3_LICENSE = BSD-3-Clause