package/libxml2: security bump to version 2.9.13

Fix the following security issues:
- [CVE-2022-23308] Use-after-free of ID and IDREF attributes
- Use-after-free in xmlXIncludeCopyRange
- Fix Null-deref-in-xmlSchemaGetComponentTargetNs
- Fix memory leak in xmlXPathCompNodeTest
- Fix null pointer deref in xmlStringGetNodeList
- Fix several memory leaks found by Coverity

https://gitlab.gnome.org/GNOME/libxml2/-/tags/v2.9.13



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