deps: bump com.diffplug.spotless:spotless-maven-plugin

Bumps [com.diffplug.spotless:spotless-maven-plugin](https://github.com/diffplug/spotless) from 3.5.1 to 3.6.0.
- [Release notes](https://github.com/diffplug/spotless/releases)
- [Changelog](https://github.com/diffplug/spotless/blob/main/CHANGES.md)
- [Commits](diffplug/spotless@maven/3.5.1...maven/3.6.0)

---
updated-dependencies:
- dependency-name: com.diffplug.spotless:spotless-maven-plugin
  dependency-version: 3.6.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

pom.xml

@@ -19,7 +19,7 @@
         <version.org.jdom>2.0.6.1</version.org.jdom>
         <version.org.junit>5.10.2</version.org.junit>
         <version.org.mockito>5.11.0</version.org.mockito>
-        <version.spotless.plugin>3.5.1</version.spotless.plugin>
+        <version.spotless.plugin>3.6.0</version.spotless.plugin>
         <spotless.skip>false</spotless.skip>
         <spotless.goal>apply</spotless.goal>
         <java.module.name>ai.timefold.solver.benchmarks</java.module.name>