Bump maven-license-plugin from 1.8 to 1.9

Bumps [maven-license-plugin](https://github.com/cloudbees/maven-license-plugin) from 1.8 to 1.9.
- [Release notes](https://github.com/cloudbees/maven-license-plugin/releases)
- [Commits](jenkinsci/license-maven-plugin@maven-license-plugin-1.8...maven-license-plugin-1.9)

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

pom.xml

@@ -415,7 +415,7 @@
         <plugin>
           <groupId>com.cloudbees</groupId>
           <artifactId>maven-license-plugin</artifactId>
-          <version>1.8</version>
+          <version>1.9</version>
         </plugin>
         <plugin> <!-- not gated by Incrementals profiles, since we want the incrementalify goal to be available from the start -->
           <groupId>io.jenkins.tools.incrementals</groupId>