Fix junit platform dependencies.

spring-cloud-contract-tools/spring-cloud-contract-gradle-plugin/build.gradle

@@ -92,6 +92,9 @@ dependencies {
 	testImplementation "org.springframework.boot:spring-boot-starter-test"
 	testImplementation localGroovy()
 	testImplementation gradleTestKit()
+	testImplementation(platform('org.junit:junit-bom:5.12.1'))
+	testImplementation('org.junit.jupiter:junit-jupiter')
+	testRuntimeOnly('org.junit.platform:junit-platform-launcher')
 }
 
 task libtest() {
@@ -101,9 +104,7 @@ task libtest() {
 }
 
 test {
-	useJUnitPlatform {
-		version = "5.12.1"
-	}
+	useJUnitPlatform ()
 	testLogging {
 		exceptionFormat = 'full'
 	}