Bump ssh-agent from 1.20 to 1.23

Bumps [ssh-agent](https://github.com/jenkinsci/ssh-agent-plugin) from 1.20 to 1.23.
- [Release notes](https://github.com/jenkinsci/ssh-agent-plugin/releases)
- [Changelog](https://github.com/jenkinsci/ssh-agent-plugin/blob/master/docs/old-changelog.md)
- [Commits](jenkinsci/ssh-agent-plugin@ssh-agent-1.20...ssh-agent-1.23)

---
updated-dependencies:
- dependency-name: org.jenkins-ci.plugins:ssh-agent
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

pom.xml

@@ -195,7 +195,7 @@
     <dependency>
       <groupId>org.jenkins-ci.plugins</groupId>
       <artifactId>ssh-agent</artifactId>
-      <version>1.20</version>
+      <version>1.23</version>
       <scope>test</scope>
       <exclusions>
         <!-- conflict with sshd module -->