Update .gitlab-ci.yml file

.gitlab-ci.yml

@@ -22,9 +22,15 @@ variables:
   CONFIG_URL: service.todo.gitlab.dergeorg.at
   CONFIG_HTTP: https
 
+
 build-job:       # Building jar file
   image: maven:3.6.3-jdk-11-slim
   stage: build
+  variables:
+    MAVEN_OPTS: "-Dmaven.repo.local=${CI_PROJECT_DIR}/.repository/"
+  cache:
+    key: maven
+    paths: [.repository/]
   script:
     - echo "$APPLICATION_TODO_SERVICE_YAML" > src/main/resources/configs/todo-service.yaml
     - mvn clean install -DskipTests && mvn package -B -e -DskipTests