Bump mavenPluginPluginVersion from 3.14.0 to 3.15.0

Bumps `mavenPluginPluginVersion` from 3.14.0 to 3.15.0.

Updates `org.apache.maven.plugin-tools:maven-plugin-annotations` from 3.14.0 to 3.15.0
- [Release notes](https://github.com/apache/maven-plugin-tools/releases)
- [Commits](apache/maven-plugin-tools@maven-plugin-tools-3.14.0...maven-plugin-tools-3.15.0)

Updates `org.apache.maven.plugins:maven-plugin-plugin` from 3.14.0 to 3.15.0
- [Release notes](https://github.com/apache/maven-plugin-tools/releases)
- [Commits](apache/maven-plugin-tools@maven-plugin-tools-3.14.0...maven-plugin-tools-3.15.0)

---
updated-dependencies:
- dependency-name: org.apache.maven.plugin-tools:maven-plugin-annotations
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.apache.maven.plugins:maven-plugin-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

pom.xml

@@ -120,7 +120,7 @@
     <whisker.site.url>file:${whisker.site.local}</whisker.site.url>
     <whisker.site.name>Whisker Website</whisker.site.name>
     <whisker.site.id>org.apache.creadur.whisker.site</whisker.site.id>
-    <mavenPluginPluginVersion>3.14.0</mavenPluginPluginVersion>
+    <mavenPluginPluginVersion>3.15.0</mavenPluginPluginVersion>
     <findbugsPluginVersion>3.0.5</findbugsPluginVersion>
   </properties>
   <!-- reporting plugins are configured according to new mvn3 standard -->