downgraded pitest plugin to 1.15 from 1.19.0-rc-1

Author: larslnde

build.gradle

@@ -276,7 +276,7 @@ dependencies {
   implementation group: 'org.camunda.bpm', name: 'camunda-external-task-client', version: versions.camunda
 
   testImplementation group: 'org.pitest', name: 'pitest', version: versions.pitest
-  testImplementation 'info.solidsoft.gradle.pitest:gradle-pitest-plugin:1.19.0-rc.1'
+  testImplementation 'info.solidsoft.gradle.pitest:gradle-pitest-plugin:1.15.0'
 
   testImplementation group: 'org.codehaus.sonar-plugins', name: 'sonar-pitest-plugin', version: versions.sonarPitest