meta: use node16 instead of node12

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

Author: yngvar-antonsson

action.yml

@@ -14,5 +14,5 @@ inputs:
     description: Deprecated. Custom key used for APT packages caching
     required: false
 runs:
-  using: 'node16'
+  using: 'node20'
   main: dist/index.js