feat!: Update action to node v20

This was done as Node16 is deprecated and the current LTS Node Versions
are v18 and v20. https://github.com/nodejs/release#release-schedule

Furthermore, GitHub Actions are transitioning the Actions Node Runner
Version from v16 to v20.

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

BREAKING CHANGE: The action will still work as before, but the move from Node v16 to v20
is considered as breaking.

action.yml

@@ -58,7 +58,7 @@ inputs:
     required: false
     default: "latest"
 runs:
-  using: "node16"
+  using: "node20"
   main: "./dist/index.js"
 branding:
   icon: "book"