Upgrade to Node 20 (#40)

https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/

Author: tfausak

action.yml

@@ -16,7 +16,7 @@ outputs:
   ideas:
     description: 'A JSON array of HLint output ideas (errors, warnings, suggestions, and so on)'
 runs:
-  using: 'node16'
+  using: 'node20'
   main: 'dist/index.js'
 branding:
   icon: 'arrow-down-circle'