chore(deps): update plugin nu.studer.rocker to v3.1

Author: renovate[bot]

buildSrc/build.gradle

@@ -1,7 +1,7 @@
 plugins {
     id "java-gradle-plugin"
     id 'groovy'
-    id 'nu.studer.rocker' version '3.0.4'
+    id 'nu.studer.rocker' version '3.1'
 }
 
 ext {