package/pigz: bump to version 2.8

Update hash of README (update year and version:
https://github.com/madler/pigz/commit/fe4894f57739e3039a2ffc2a2a360d35e19bacbe)

https://zlib.net/pipermail/pigz-announce_zlib.net/2023-August/000018.html

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/pigz/pigz.hash

@@ -1,5 +1,5 @@
 # From http://zlib.net/pigz
-sha256  b4c9e60344a08d5db37ca7ad00a5b2c76ccb9556354b722d56d55ca7e8b1c707  pigz-2.7.tar.gz
+sha256  eb872b4f0e1f0ebe59c9f7bd8c506c4204893ba6a8492de31df416f0d5170fd0  pigz-2.8.tar.gz
 
 # Locally calculated
-sha256  67e2b9e30e924724a9d72549a6004ed15a041f51d9ea9ab781e048fa27ae07a2  README
+sha256  328634933a65dbc7f97a0f51df52741dc67f593bbe9eccabc9eedc6934c4983b  README

package/pigz/pigz.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-PIGZ_VERSION = 2.7
+PIGZ_VERSION = 2.8
 PIGZ_SITE = http://zlib.net/pigz
 PIGZ_DEPENDENCIES = zlib
 HOST_PIGZ_DEPENDENCIES = host-zlib