Bump simple-theme-plugin from 0.5 to 0.6 (#1535)

Bumps [simple-theme-plugin](https://github.com/jenkinsci/simple-theme-plugin) from 0.5 to 0.6.
- [Release notes](https://github.com/jenkinsci/simple-theme-plugin/releases)
- [Changelog](https://github.com/jenkinsci/simple-theme-plugin/blob/master/CHANGELOG.old.md)
- [Commits](jenkinsci/simple-theme-plugin@simple-theme-plugin-0.5...simple-theme-plugin-0.6)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

integrations/pom.xml

@@ -284,7 +284,7 @@
     <dependency>
       <groupId>org.jenkins-ci.plugins</groupId>
       <artifactId>simple-theme-plugin</artifactId>
-      <version>0.5</version>
+      <version>0.6</version>
       <scope>test</scope>
     </dependency>