Bump spotless-maven-plugin from 2.30.0 to 2.31.0

Bumps [spotless-maven-plugin](https://github.com/diffplug/spotless) from 2.30.0 to 2.31.0.
- [Release notes](https://github.com/diffplug/spotless/releases)
- [Changelog](https://github.com/diffplug/spotless/blob/main/CHANGES.md)
- [Commits](https://github.com/diffplug/spotless/compare/lib/2.30.0...lib/2.31.0)

---
updated-dependencies:
- dependency-name: com.diffplug.spotless:spotless-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...
Signed-off-by: Ndependabot[bot] <support@github.com>

pom.xml

@@ -97,7 +97,7 @@ THE SOFTWARE.
     <access-modifier.version>1.30</access-modifier.version>
     <antlr.version>4.11.1</antlr.version>
     <bridge-method-injector.version>1.25</bridge-method-injector.version>
-    <spotless.version>2.30.0</spotless.version>
+    <spotless.version>2.31.0</spotless.version>
     <winstone.version>6.7</winstone.version>
   </properties>