Update dependency com.diffplug.spotless:spotless-maven-plugin to v3

Author: renovate[bot]

pom.xml

@@ -57,7 +57,7 @@
     <maven-enforcer-plugin.version>3.6.1</maven-enforcer-plugin.version>
     <skuzzle-imports-enforcer.version>3.0.0</skuzzle-imports-enforcer.version>
     <flatten-maven-plugin.version>1.7.3</flatten-maven-plugin.version>
-    <spotless-maven-plugin.version>2.46.1</spotless-maven-plugin.version>
+    <spotless-maven-plugin.version>3.0.0</spotless-maven-plugin.version>
     <versions-maven-plugin.version>2.19.1</versions-maven-plugin.version>
   </properties>