This update for go-sendxmpp fixes the following issues:

Update to 0.16.0:

- CVE-2026-1229: circl: The CombinedMult function produces an incorrect value (boo#1265538).
- CVE-2026-39821: net: Failure to reject ASCII-only Punycode-encoded labels allows for validation bypass and privilege escalation (boo#1266617).