Short-circuit global `before_script`

.gitlab-ci.yml

@@ -22,6 +22,8 @@ lint-dockerfile:
 lint-shell-script:
   stage: test
   image: koalaman/shellcheck-alpine:latest
+  before_script:
+    - shellcheck -V
   script:
     - find . -name "*.sh" -exec shellcheck {} \;