c-ares vulnerabilities

USN-6164-1 fixed several vulnerabilities in c-ares. This update provides
the corresponding update for Ubuntu 16.04 LTS and Ubuntu 18.04 LTS.

Original advisory details:

Hannes Moesl discovered that c-ares incorrectly handled certain ipv6
addresses. An attacker could use this issue to cause c-ares to crash,
resulting in a denial of service, or possibly execute arbitrary code.
(CVE-2023-31130)

Xiang Li discovered that c-ares incorrectly handled certain UDP packets. A
remote attacker could possibly use this issue to cause c-res to crash,
resulting in a denial of service. (CVE-2023-32067)