Bump io.jenkins.tools.bom:bom-2.138.x from 3 to 4

Bumps [io.jenkins.tools.bom:bom-2.138.x](https://github.com/jenkinsci/bom) from 3 to 4.
- [Release notes](https://github.com/jenkinsci/bom/releases)
- [Commits](https://github.com/jenkinsci/bom/commits)

---
updated-dependencies:
- dependency-name: io.jenkins.tools.bom:bom-2.138.x
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

pom.xml

@@ -61,7 +61,7 @@
       <dependency>
         <groupId>io.jenkins.tools.bom</groupId>
         <artifactId>bom-2.138.x</artifactId>
-        <version>3</version>
+        <version>4</version>
         <scope>import</scope>
         <type>pom</type>
       </dependency>