Block update to ssh-credentials plugin 326.v7fcb_a_ef6194b_

jenkinsci/ssh-credentials-plugin#199 makes the
trilead-api plugin an optional dependency of the ssh-credentials plugin.
That exposed a latent issue in the subversion plugin that is resolved
in jenkinsci/subversion-plugin#284 .

jenkinsci#3050 describes the details of
the test failures in the plugin bill of mateerials.  The failing tests
can be seen with the commands:

 PLUGINS=subversion TEST=CompareAgainstBaselineCallableTest bash local-test.sh
 PLUGINS=mina-sshd-api-core LINE=weekly bash local-test.sh

No need to block later releases, since the pull request thet fixes the
issue has been submitted and is ready for review.

.github/dependabot.yml

@@ -8,6 +8,10 @@ updates:
   - package-ecosystem: "maven"
     open-pull-requests-limit: 25
     directory: "/bom-weekly"
+    ignore:
+      # Remove when https://github.com/jenkinsci/subversion-plugin/pull/284 is released
+      - dependency-name: "org.jenkins-ci.plugins:ssh-credentials"
+        versions: ["326.v7fcb_a_ef6194b_"]
     schedule:
       interval: "daily"
   - package-ecosystem: "github-actions"