Update .gitlab-ci.yml

.gitlab-ci.yml

@@ -11,6 +11,7 @@ stages:
   - build
   - verification
   - publish
+  - cleanup
 
 
 
@@ -110,3 +111,14 @@ docker-push-tag:
   script:
     - docker load -i build/image.tar
     - docker push $DOCKER_NAMESPACE/$PROJECT_NAME:$CI_COMMIT_TAG
+
+cleanup:
+  stage: cleanup
+  image: docker:git
+  tags:
+    - cache
+  script:
+    - docker system prune -a -f || true 
+    - rm -rf build/ || true
+  when: always
+  allow_failure: true