Bump com.diffplug.spotless from 6.12.1 to 6.13.0 in /examples/extension (#7581)

Author: dependabot[bot]

examples/extension/build.gradle

@@ -11,7 +11,7 @@ plugins {
   See https://imperceptiblethoughts.com/shadow/ for more details about Shadow plugin.
    */
   id "com.github.johnrengelman.shadow" version "7.1.2"
-  id "com.diffplug.spotless" version "6.12.1"
+  id "com.diffplug.spotless" version "6.13.0"
 
   id "io.opentelemetry.instrumentation.muzzle-generation" version "1.23.0-alpha-SNAPSHOT"
   id "io.opentelemetry.instrumentation.muzzle-check" version "1.23.0-alpha-SNAPSHOT"