Bump com.diffplug.spotless from 6.5.2 to 6.6.1 (#3356)

Bumps com.diffplug.spotless from 6.5.2 to 6.6.1.

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

build.gradle

@@ -48,7 +48,7 @@ plugins {
   id 'lifecycle-base'
   id 'opensearch.docker-support'
   id 'opensearch.global-build-info'
-  id "com.diffplug.spotless" version "6.5.2" apply false
+  id "com.diffplug.spotless" version "6.6.1" apply false
   id "org.gradle.test-retry" version "1.4.0" apply false
   id "test-report-aggregation"
   id 'jacoco-report-aggregation'