adding firebase preview action

.github/workflows/firebase-preview.yml

@@ -0,0 +1,35 @@
+name: Deploy Preview
+'on': pull_request
+jobs:
+  build_and_preview:
+    if: '${{ github.event.pull_request.head.repo.full_name == github.repository }}'
+    runs-on: ubuntu-latest
+    steps:
+      
+      - name: Hugo setup
+        uses: peaceiris/actions-hugo@v2.4.12
+        env:
+          ACTIONS_ALLOW_UNSECURE_COMMANDS: 'true'
+
+      - name: Check out code into the Go module directory
+        uses: actions/checkout@v2
+        with:
+          submodules: true  # Fetch Hugo themes (true OR recursive)
+          fetch-depth: 0    # Fetch all history for .GitInfo and .Lastmod
+
+      - name: Build with Hugo
+        env:
+          # For maximum backward compatibility with Hugo modules
+          HUGO_ENVIRONMENT: production
+          HUGO_ENV: production
+        run: |
+          hugo --minify -s exampleSite --themesDir ../.. -d ../docs --baseURL https://blowfish.page
+
+      - name: Deploy preview
+        uses: FirebaseExtended/action-hosting-deploy@v0
+        with:
+          repoToken: '${{ secrets.GITHUB_TOKEN }}'
+          firebaseServiceAccount: '${{ secrets.FIREBASE_SERVICE_ACCOUNT_HOMEPAGE_A0C38 }}'
+          expires: 30d
+          channelId: preview
+          projectId: blowfish-21fff