fix invalid action syntax

Author: Josh-Cena

.github/workflows/deploy-gh-pages.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Build website
         run: yarn build
       - name: Deploy
-        if: github.event_name == "push"
+        if: ${{ github.event_name == 'push' }}
         uses: peaceiris/actions-gh-pages@v3
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}