build(deps): bump com.diffplug.spotless from 6.19.0 to 6.20.0

Bumps com.diffplug.spotless from 6.19.0 to 6.20.0.

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

Signed-off-by: dependabot[bot] <support@github.com>

build.gradle

@@ -9,7 +9,7 @@ plugins {
     id 'checkstyle'
 
     // community plugins
-    id 'com.diffplug.spotless' version '6.19.0'
+    id 'com.diffplug.spotless' version '6.20.0'
     id 'net.ltgt.errorprone' version '3.1.0'
     id 'com.github.spotbugs' version '5.0.14'
     id 'org.ajoberstar.grgit' version '5.2.0'