run bash syntax checker on ENTRYPOINT script

.gitlab-ci.yml

@@ -18,6 +18,8 @@ before_script:
 build:
   stage: build
   script:
+    - apk add --no-cache bash
+    - /bin/bash -n gitlab-ci-git-buildpackage
     - echo Building ${RELEASE_IMAGE}
     - docker build -t $TEST_IMAGE .
     - docker push $TEST_IMAGE