GH Actions: add actionlint job

This job checks the GH Actions workflows against syntax errors and other problems.

Author: jrfnl

.github/workflows/cs.yml

@@ -8,6 +8,10 @@ on:
   workflow_dispatch:
 
 jobs:
+  actionlint:
+    name: 'Lint GH Action workflows'
+    uses: Yoast/.github/.github/workflows/reusable-actionlint.yml@main
+
   checkcs:
     name: 'Basic CS and QA checks'
     runs-on: ubuntu-latest