chore: Update Ribose CVE advisory URL

Author: ribose-jeffreylau

_posts/2025-11-20-rnp-release-0-18-1.adoc

@@ -177,7 +177,7 @@ We thank Johannes for the responsible disclosure and coordination.
 * Red Hat CVE: https://access.redhat.com/security/cve/cve-2025-13402
 * Red Hat Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2415863
 * Red Hat CSAF: https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-13402.json
-* Ribose CNA Advisory: https://cve.ribose.com/advisories/ra-2025-11-20/
+* Ribose CNA Advisory: https://open.ribose.com/advisories/ra-2025-11-20/
 * Release 0.18.1: https://github.com/rnpgp/rnp/releases/tag/v0.18.1
 
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