OZG-7906 get parent version from pom for server and job

Jenkinsfile

@@ -49,8 +49,8 @@ pipeline {
                 script {
                     FAILED_STAGE = env.STAGE_NAME
                     def rootVersion = getPomVersion('pom.xml')
-                    def jobVersion = getPomVersion('aggregation-manager-job/pom.xml')
-                    def serverVersion = getPomVersion('aggregation-manager-server/pom.xml')
+                    def jobVersion = getParentPomVersion('aggregation-manager-job/pom.xml')
+                    def serverVersion = getParentPomVersion('aggregation-manager-server/pom.xml')
 
                     if(rootVersion != jobVersion) {
                         error("Version in aggregation-manager-job stimmt nicht mit dem parent überein.")
@@ -280,6 +280,10 @@ String getPomVersion(String pomFile){
     return pom.version
 }
 
+String getParentPomVersion(String filePath) {
+    def pom = readMavenPom file: filePath
+    return pom.parent.version
+}
 
 Void sendFailureMessage() {
     def room = ''