Bump org.jenkins-ci.plugins:plugin from 5.5 to 5.6

Bumps [org.jenkins-ci.plugins:plugin](https://github.com/jenkinsci/plugin-pom) from 5.5 to 5.6.
- [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-5.5...plugin-5.6)

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

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

Author: dependabot[bot]

pom.xml

@@ -28,7 +28,7 @@
     <parent>
         <groupId>org.jenkins-ci.plugins</groupId>
         <artifactId>plugin</artifactId>
-        <version>5.5</version>
+        <version>5.6</version>
         <relativePath/>
     </parent>
     <groupId>org.jenkins-ci.plugins.workflow</groupId>