package/opencv4: security bump to version 4.8.1

Also, bump package/opencv4-contrib to in lock-step.

This addresses both CVE-2023-2617 and CVE-2023-2618, that have been
fixed in OpenCV 4.8.0.

Signed-off-by: Woodrow Douglass <wdouglass@carnegierobotics.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit a01490397e4cc11155b3c396ded382eefeef4f12)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/opencv4-contrib/opencv4-contrib.hash

@@ -1,3 +1,3 @@
 # Locally calculated
-sha256  1777d5fd2b59029cf537e5fd6f8aa68d707075822f90bde683fcde086f85f7a7  opencv4-contrib-4.6.0.tar.gz
+sha256  0c082a0b29b3118f2a0a1856b403bb098643af7b994a0080f402a12159a99c6e  opencv4-contrib-4.8.1.tar.gz
 sha256  cfc7749b96f63bd31c3c42b5c471bf756814053e847c10f3eb003417bc523d30  LICENSE

package/opencv4-contrib/opencv4-contrib.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-OPENCV4_CONTRIB_VERSION = 4.6.0
+OPENCV4_CONTRIB_VERSION = 4.8.1
 OPENCV4_CONTRIB_SITE = $(call github,opencv,opencv_contrib,$(OPENCV4_CONTRIB_VERSION))
 OPENCV4_CONTRIB_INSTALL_TARGET = FALSE
 OPENCV4_CONTRIB_LICENSE = Apache-2.0

package/opencv4/opencv4.hash

@@ -1,3 +1,3 @@
 # Locally calculated
-sha256  1ec1cba65f9f20fe5a41fda1586e01c70ea0c9a6d7b67c9e13edf0cfe2239277  opencv4-4.6.0.tar.gz
+sha256  62f650467a60a38794d681ae7e66e3e8cfba38f445e0bf87867e2f2cdc8be9d5  opencv4-4.8.1.tar.gz
 sha256  cfc7749b96f63bd31c3c42b5c471bf756814053e847c10f3eb003417bc523d30  LICENSE

package/opencv4/opencv4.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-OPENCV4_VERSION = 4.6.0
+OPENCV4_VERSION = 4.8.1
 OPENCV4_SITE = $(call github,opencv,opencv,$(OPENCV4_VERSION))
 OPENCV4_INSTALL_STAGING = YES
 OPENCV4_LICENSE = Apache-2.0