Update dependency com.diffplug.spotless to v8.9.0

| datasource | package                                                   | from  | to    |
| ---------- | --------------------------------------------------------- | ----- | ----- |
| maven      | com.diffplug.spotless:com.diffplug.spotless.gradle.plugin | 8.8.0 | 8.9.0 |

Author: renovate[bot]

gradle/libs.versions.toml

@@ -10,7 +10,7 @@ ktor = "3.5.1"
 logback = "1.6.1"
 postgresql = "42.7.13"
 slugify = "4.0.1"
-spotless = "8.8.0"
+spotless = "8.9.0"
 sqldelight = "2.3.2"
 testcontainers = "1.21.4"
 version-catalog-update = "1.1.0"