Bump org.jenkins-ci.plugins:plugin from 5.7 to 5.9

Bumps [org.jenkins-ci.plugins:plugin](https://github.com/jenkinsci/plugin-pom) from 5.7 to 5.9.
- [Release notes](https://github.com/jenkinsci/plugin-pom/releases)
- [Changelog](https://github.com/jenkinsci/plugin-pom/blob/master/CHANGELOG.md)
- [Commits](jenkinsci/plugin-pom@plugin-5.7...plugin-5.9)

---
updated-dependencies:
- dependency-name: org.jenkins-ci.plugins:plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pom.xml

@@ -29,7 +29,7 @@ THE SOFTWARE.
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>5.7</version>
+    <version>5.9</version>
     <relativePath/>
   </parent>