Bump org.spockframework:spock-bom

Bumps [org.spockframework:spock-bom](https://github.com/spockframework/spock) from 2.4-M4-groovy-3.0 to 2.4-M6-groovy-4.0.
- [Release notes](https://github.com/spockframework/spock/releases)
- [Changelog](https://github.com/spockframework/spock/blob/master/docs/release_notes.adoc)
- [Commits](https://github.com/spockframework/spock/commits)

---
updated-dependencies:
- dependency-name: org.spockframework:spock-bom
  dependency-version: 2.4-M6-groovy-4.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -3,7 +3,7 @@ project = "2025.1-SNAPSHOT"
 
 api = "2024.2"
 snakeyaml = "2.5"
-spock = "2.4-M4-groovy-3.0"
+spock = "2.4-M6-groovy-4.0"
 bytebuddy = "1.17.7"
 
 # plugins