Merge pull request #230 from buildkite-plugins/renovate/shellcheck-1.x

Update buildkite plugin shellcheck to v1.4.0

Author: james2791

.buildkite/pipeline.yml

@@ -15,5 +15,5 @@ steps:
 
   - label: ":bash: Shellcheck"
     plugins:
-      - shellcheck#v1.3.0:
+      - shellcheck#v1.4.0:
           files: hooks/*