Bump com.diffplug.spotless from 6.18.0 to 6.19.0 (#815)

Author: dependabot[bot]

build.gradle

@@ -4,7 +4,7 @@ plugins {
   id 'maven-publish'
   id 'signing'
   id 'pmd' // code check, working on source code
-  id 'com.diffplug.spotless' version '6.18.0'//code format
+  id 'com.diffplug.spotless' version '6.19.0'//code format
   id 'com.github.spotbugs' version '5.0.14' // code check, working on byte code
   id 'de.undercouch.download' version '5.4.0'
   id 'kr.motd.sphinx' version '2.10.1' // documentation generation