build(deps): bump com.diffplug.spotless from 6.15.0 to 6.16.0 (#858)

Bumps com.diffplug.spotless from 6.15.0 to 6.16.0.

---
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>

buildSrc/build.gradle.kts

@@ -1,6 +1,6 @@
 plugins {
     `kotlin-dsl`
-    id("com.diffplug.spotless") version "6.15.0"
+    id("com.diffplug.spotless") version "6.16.0"
 }
 
 repositories {