Update .gitlab-ci.yml file

.gitlab-ci.yml

@@ -19,7 +19,8 @@
 stages:          # List of stages for jobs, and their order of execution
   - build
 
-build-job:       # This job runs in the build stage, which runs first.
+build-job: 
+  image: maven:3-jdk-8      # This job runs in the build stage, which runs first.
   stage: build
   script:
     - echo "Checking the code syntax..."