fix(deps): update spock monorepo to v2.4-m6-groovy-4.0 (#285)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

gradle/libs.versions.toml

@@ -6,7 +6,7 @@ googleJavaFormat = "1.25.2"
 jacoco = "0.8.12"
 junit = "5.12.2"
 pmd = "7.11.0"
-spock = "2.4-M5-groovy-4.0"
+spock = "2.4-M6-groovy-4.0"
 spring-boot-platform = "3.4.4"
 
 [libraries]