You can use GITHUB_TOKEN already provided by Github Actions (#100)

Reference: https://help.github.com/en/actions/automating-your-workflow-with-github-actions/authenticating-with-the-github_token

.github/workflows/deploy.yml

@@ -32,6 +32,6 @@ jobs:
     - name: Deploy microsite
       uses: peaceiris/actions-gh-pages@v2
       env:
-        ACTIONS_DEPLOY_KEY: ${{ secrets.ACTIONS_DEPLOY_KEY }}
+        ACTIONS_DEPLOY_KEY: ${{ secrets.GITHUB_TOKEN }}
         PUBLISH_BRANCH: gh-pages
         PUBLISH_DIR: ./gen-docs