Bump plugin from 4.6 to 4.15

Bumps [plugin](https://github.com/jenkinsci/plugin-pom) from 4.6 to 4.15.
- [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-4.6...plugin-4.15)

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

pom.xml

@@ -3,7 +3,7 @@
   <parent>
     <groupId>org.jenkins-ci.plugins</groupId>
     <artifactId>plugin</artifactId>
-    <version>4.6</version>
+    <version>4.15</version>
     <relativePath />
   </parent>