Bump com.diffplug.spotless from 8.8.0 to 8.9.0 (#36)

Bumps com.diffplug.spotless from 8.8.0 to 8.9.0.

---
updated-dependencies:
- dependency-name: com.diffplug.spotless
  dependency-version: 8.9.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]

gradle/libs.versions.toml

@@ -7,7 +7,7 @@ junit = "6.1.2"
 junit-platform = "6.1.2"
 spotbugs = "6.5.9"
 spotbugs-annotations = "4.10.3"
-spotless = "8.8.0"
+spotless = "8.9.0"
 
 [libraries]
 awaitility = { module = "org.awaitility:awaitility", version.ref = "awaitility" }