The Firebase CLI automatically generates a configuration file for setting up a GitHub Action to deploy previews, which is a handy feature. It's quite beneficial, especially if you're working with the Firebase webframework, so I highly recommend using it.

# This file was auto-generated by the Firebase CLI
# https://github.com/firebase/firebase-tools

name: Deploy to Firebase Hosting on PR
"on": pull_request
jobs:
  build_and_preview:
    if: "${{ github.event.pull_request.head.repo.full_name == github.repository }}"
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - run: cd hosting && npm ci
      - run: npm ci && npx firebase experiments:enable webframeworks
      - uses: FirebaseExtended/action-hosting-deploy@v0
        with:
          repoToken: "${{ secrets.GITHUB_TOKEN }}"
          firebaseServiceAccount: "${{ secrets.FIREBASE_SERVICE_ACCOUNT_YSN_BLOG }}"
          projectId: ysn-blog