Please use https://github.com/apps/changeset-bot instead of this because this doesn't work on forked PRs
This action for Changesets comments on PRs with whether a PR has a changeset or not and links to documentation explaining to contributors how to create a changeset.
Create a file at .github/workflows/changeset-check.yml with the following content.
name: Changeset Check
on: pull_request
jobs:
  check:
    name: Changeset Check
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@master
      - name: Comment on PR
        uses: changesets/check-action@master
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}