Update .gitlab-ci.yml

.gitlab-ci.yml

+stages:          # List of stages for jobs, and their order of execution
+  - deploy
+build-job:       # This job runs in the build stage, which runs first.
+  stage: check
+  script:
+    - apk add openjdk11-jre-headless
+    - mvn compile assembly:single
+  artifacts:
+     name: "release"
+     path:
+         - target/corpus-web-service-1.0-SNAPSHOT.jar