Replace GNOME gitlab URL with GitHub mirror

GitHub is more reliable host when downloading source code for packages
as in case of server maintenance, which often happens, it causes builds
from scratch to fail.

Author: petk

cmake/cmake/modules/Packages/LibXml2.cmake

@@ -38,7 +38,7 @@ set(PHP_LIBXML2_DOWNLOAD_VERSION 2.12.7)
 
 FetchContent_Declare(
   LibXml2
-  URL https://gitlab.gnome.org/GNOME/libxml2/-/archive/v${PHP_LIBXML2_DOWNLOAD_VERSION}/libxml2-v${PHP_LIBXML2_DOWNLOAD_VERSION}.tar.gz
+  URL https://github.com/GNOME/libxml2/archive/refs/tags/v${PHP_LIBXML2_DOWNLOAD_VERSION}.tar.gz
   EXCLUDE_FROM_ALL
   SYSTEM
   FIND_PACKAGE_ARGS