Merge pull request #277 from buildkite-plugins/renovate/shellcheck-1.x

chore(deps): update buildkite plugin shellcheck to v1.4.0

Author: james2791

.buildkite/pipeline.yml

@@ -1,7 +1,7 @@
 steps:
   - label: ":shell: Shellcheck"
     plugins:
-      - shellcheck#v1.3.0:
+      - shellcheck#v1.4.0:
           files:
             - hooks/**
             - commands/**