Bump org.spockframework:spock-core

Bumps [org.spockframework:spock-core](https://github.com/spockframework/spock) from 2.4-M1-groovy-3.0 to 2.4-M4-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-core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

build.gradle

@@ -51,7 +51,7 @@ repositories {
 dependencies {
     implementation 'org.ow2.asm:asm:9.6'
 
-    testImplementation 'org.spockframework:spock-core:2.4-M1-groovy-3.0'
+    testImplementation 'org.spockframework:spock-core:2.4-M4-groovy-4.0'
 
     asciidoctorExt 'com.bmuschko:asciidoctorj-tabbed-code-extension:0.3'
 }