Update book.yml

Author: LegNeato

.github/workflows/book.yml

@@ -50,11 +50,8 @@ jobs:
           mdbook build -d gh-pages/master docs/book
 
       - name: Deploy
-        uses: peaceiris/actions-gh-pages@v2.5.1
+        uses: peaceiris/actions-gh-pages@v3
         with:
-          emptyCommits: false
+          github_token: ${{ secrets.GITHUB_TOKEN }}
           keepFiles: true
-        env:
-          ACTIONS_DEPLOY_KEY: ${{ secrets.ACTIONS_DEPLOY_KEY }}
-          PUBLISH_BRANCH: gh-pages
-          PUBLISH_DIR: docs/book/gh-pages
+          publish_dir: docs/book/gh-pages