chore(dev-deps): bump spotless-plugin-gradle in /buildSrc

Bumps spotless-plugin-gradle from 6.4.1 to 6.4.2.

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

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

buildSrc/build.gradle.kts

@@ -9,7 +9,7 @@ repositories {
 }
 
 dependencies {
-    implementation("com.diffplug.spotless:spotless-plugin-gradle:6.4.1")
+    implementation("com.diffplug.spotless:spotless-plugin-gradle:6.4.2")
     implementation("io.github.gradle-nexus:publish-plugin:1.1.0")
     implementation("net.ltgt.gradle:gradle-errorprone-plugin:2.0.2")
     implementation("org.sonarsource.scanner.gradle:sonarqube-gradle-plugin:3.3")