dnsdist: Update to 1.9.9

dnsdist: Update to 1.9.9

We released PowerDNS DNSdist 1.9.9 today, an emergency release fixing a security issue tracked as CVE-2025-30194 where a remote, unauthenticated attacker can cause a denial of service via a crafted DNS over HTTPS connection. The issue was reported to us via our public GitHub tracker, so once it was clear that the issue had a security impact we prepared to release a new version as soon as possible.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>