Use it in your Raku modules like so:

on: [ push, pull_request ]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - name: Test via install
        uses: JJ/raku-test-action@main

It will install dependencies, test, and then cache installation so you don't have to do it again in the future. It's using the latest version of Raku, whatever that is at the moment.