libxml2: upgrade 2.13.6 -> 2.14.3

libxml2: upgrade 2.13.6 -> 2.14.3

Handle CVE-2025-32414 and CVE-2025-32415.

* rebased install-tests.patch
* removed testsuite testThreads (merged into runtest.c)
  * https://gitlab.gnome.org/GNOME/libxml2/-/commit/481fd6bbee029e15a6a4015e5160a332d7c18cba
* removed IPv6 option (as part of with ftp support removal)
  * https://gitlab.gnome.org/GNOME/libxml2/-/commit/dba1ed85a320c36807ee09f44d09fd30852b9370
* added testsuites testlimits testparser (already present before but not executed)

License-Update: Mention contributors in Copyright
https://gitlab.gnome.org/GNOME/libxml2/-/commit/4bd66d4549b2e8925a752e0daac3a189d2fec8f7

Signed-off-by: Peter Marko <peter.marko@siemens.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>