[4.0.x] Bump com.diffplug.spotless:spotless-maven-plugin

Bumps [com.diffplug.spotless:spotless-maven-plugin](https://github.com/diffplug/spotless) from 3.0.0 to 3.1.0.
- [Release notes](https://github.com/diffplug/spotless/releases)
- [Changelog](https://github.com/diffplug/spotless/blob/main/CHANGES.md)
- [Commits](diffplug/spotless@lib/3.0.0...lib/3.1.0)

---
updated-dependencies:
- dependency-name: com.diffplug.spotless:spotless-maven-plugin
  dependency-version: 3.1.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

pom.xml

@@ -164,7 +164,7 @@
         <plugin>
           <groupId>com.diffplug.spotless</groupId>
           <artifactId>spotless-maven-plugin</artifactId>
-          <version>3.0.0</version>
+          <version>3.1.0</version>
         </plugin>
         <plugin>
           <groupId>com.mycila</groupId>