Bump org.spockframework:spock-core in /junit5-multiple-engines

Bumps [org.spockframework:spock-core](https://github.com/spockframework/spock) from 2.4-M2-groovy-4.0 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] <support@github.com>

junit5-multiple-engines/build.gradle.kts

@@ -58,7 +58,7 @@ dependencies {
     testRuntimeOnly("org.spekframework.spek2:spek-runner-junit5:$spekVersion")
 
     // Spock2
-    testImplementation("org.spockframework:spock-core:2.4-M2-groovy-4.0") {
+    testImplementation("org.spockframework:spock-core:2.4-M4-groovy-4.0") {
         because("allows Spock specifications to run")
     }
     testImplementation(platform("org.apache.groovy:groovy-bom:4.0.20")) {