Bump bom-2.176.x from 13 to 15

Bumps [bom-2.176.x](https://github.com/jenkinsci/pom) from 13 to 15.
- [Release notes](https://github.com/jenkinsci/pom/releases)
- [Changelog](https://github.com/jenkinsci/pom/blob/master/CHANGELOG.md)
- [Commits](https://github.com/jenkinsci/pom/commits)

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

Author: dependabot-preview[bot]

pom.xml

@@ -56,7 +56,7 @@
       <dependency>
         <groupId>io.jenkins.tools.bom</groupId>
         <artifactId>bom-2.176.x</artifactId>
-        <version>13</version>
+        <version>15</version>
         <scope>import</scope>
         <type>pom</type>
       </dependency>