fix method call

Jenkinsfile

@@ -61,7 +61,9 @@ pipeline {
         success {
 
             script {
-                if ({env.BRANCH_NAME}.startsWith('pr-')) {
+                #!groovy
+
+                if (env.BRANCH_NAME.startsWith('pr-')) {
 
 //                git url: "git@gogs.informatik.hs-fulda.de:SteffenN/Multi-Chess.git",
 //                        credentialsId: 'jenkins_ssh_key',