databases/libgda6: Unbreak build with libxml2 2.14

Unbreak the build after the libxml2 upgrade.  The PORTREVISION was bumped
for the libxml2 upgrade to no need to do it again.

Upstream issue: https://gitlab.gnome.org/GNOME/libgda/-/issues/273

PR:		287888
MFH:		2025Q3