fix jenkins file

Jenkinsfile

@@ -5,13 +5,13 @@ pipeline {
         stage('Build') {
             steps {
                 echo 'Building..'
-                ./gradlew clean build
+                sh './gradlew clean build'
             }
         }
         stage('Test') {
             steps {
                 echo 'Testing..'
-                ./gradlew test
+                sh './gradlew test'
             }
         }
     }