Merge pull request #458 from buildkite-plugins/renovate/shellcheck-1.x

Update buildkite plugin shellcheck to v1.4.0

Author: james2791

.buildkite/pipeline.yml

@@ -7,7 +7,7 @@ env:
 steps:
   - label: ":shell: Shellcheck"
     plugins:
-      shellcheck#v1.3.0:
+      shellcheck#v1.4.0:
         files:
           - hooks/**
           - lib/**