xerces-c vulnerability

USN-6579-1 fixed a vulnerability in Xerces-C++. This update provides the
corresponding update for Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 23.04
and Ubuntu 23.10.

Original advisory details:

It was discovered that Xerces-C++ was not properly handling memory
management operations when parsing XML data containing external DTDs,
which could trigger a use-after-free error. If a user or automated system
were tricked into processing a specially crafted XML document, an attacker
could possibly use this issue to cause a denial of service or execute
arbitrary code.