Bump com.diffplug.spotless:spotless-plugin-gradle from 8.2.0 to 8.4.0

Bumps [com.diffplug.spotless:spotless-plugin-gradle](https://github.com/diffplug/spotless) from 8.2.0 to 8.4.0.
- [Release notes](https://github.com/diffplug/spotless/releases)
- [Changelog](https://github.com/diffplug/spotless/blob/main/CHANGES.md)
- [Commits](diffplug/spotless@gradle/8.2.0...gradle/8.4.0)

---
updated-dependencies:
- dependency-name: com.diffplug.spotless:spotless-plugin-gradle
  dependency-version: 8.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

buildSrc/build.gradle.kts

@@ -16,7 +16,7 @@ dependencies {
   // Spotless dropped Java 8 support in version 2.33.0
   // spotless-plugin-gradle dropped Java <17 support in version 8.0.0
   if (JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_17)) {
-    implementation("com.diffplug.spotless:spotless-plugin-gradle:8.2.0")
+    implementation("com.diffplug.spotless:spotless-plugin-gradle:8.4.0")
     implementation("io.github.cosmicsilence:gradle-scalafix:0.2.2")
   }
 }