libxml2: update to 2.13.6

Release Notes:
https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.13.5
https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.13.6

Fixes: CVE-2025-24928 CVE-2024-56171

Link: https://github.com/openwrt/openwrt/pull/18194
Signed-off-by: Nick Hainke <[email protected]>

package/libs/libxml2/Makefile

@@ -1,12 +1,12 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=libxml2
-PKG_VERSION:=2.13.4
+PKG_VERSION:=2.13.6
 PKG_RELEASE:=1
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
 PKG_SOURCE_URL:=@GNOME/libxml2/$(basename $(PKG_VERSION))
-PKG_HASH:=65d042e1c8010243e617efb02afda20b85c2160acdbfbcb5b26b80cec6515650
+PKG_HASH:=f453480307524968f7a04ec65e64f2a83a825973bcd260a2e7691be82ae70c96
 
 PKG_LICENSE:=MIT
 PKG_LICENSE_FILES:=COPYING