textproc/libxml2: Update to 2.11.7

Fixes CVE-2024-25062

Reference:
https://www.cve.org/CVERecord?id=CVE-2024-25062

Changelog: https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.11.7

PR: 276900
Approved by: desktop (fluffy)
Sponsored by: Blinkinblox
Exp-run by: antoine