Bump spotless-plugin-gradle from 6.11.0 to 6.12.0 (#4987)

Bumps [spotless-plugin-gradle](https://github.com/diffplug/spotless) from 6.11.0 to 6.12.0.
- [Release notes](https://github.com/diffplug/spotless/releases)
- [Changelog](https://github.com/diffplug/spotless/blob/main/CHANGES.md)
- [Commits](diffplug/spotless@gradle/6.11.0...gradle/6.12.0)

---
updated-dependencies:
- dependency-name: com.diffplug.spotless:spotless-plugin-gradle
  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>

buildSrc/build.gradle.kts

@@ -14,7 +14,7 @@ repositories {
 dependencies {
   implementation("com.google.auto.value:auto-value-annotations:1.10.1")
   // When updating, update above in plugins too
-  implementation("com.diffplug.spotless:spotless-plugin-gradle:6.11.0")
+  implementation("com.diffplug.spotless:spotless-plugin-gradle:6.12.0")
   // Needed for japicmp but not automatically brought in for some reason.
   implementation("com.google.guava:guava:31.1-jre")
   implementation("com.squareup:javapoet:1.13.0")