Update dependency com.diffplug.spotless:spotless-plugin-gradle to v6.23.3

Author: renovate[bot]

buildSrc/build.gradle

@@ -7,6 +7,6 @@ repositories {
 }
 
 dependencies {
-    implementation group: 'com.diffplug.spotless', name: 'spotless-plugin-gradle', version: '6.18.0'
+    implementation group: 'com.diffplug.spotless', name: 'spotless-plugin-gradle', version: '6.23.3'
     implementation group: 'com.github.jakemarsden', name: 'git-hooks-gradle-plugin', version: '0.0.2'
 }