Update CVE-2020-21514.yml

Link to the GHSA advisory for CVE-2020-21514.

Author: postmodern

gems/fluentd/CVE-2020-21514.yml

@@ -2,7 +2,7 @@
 gem: fluentd
 cve: 2020-21514
 ghsa: wrxf-x8rm-6ggg
-url: https://github.com/fluent/fluentd/issues/2722
+url: https://github.com/advisories/GHSA-wrxf-x8rm-6ggg
 title: Fluent Fluentd and Fluent-ui use default password
 date: 2023-04-04
 description: |