Update demo deployment action to use different action package

.github/workflows/demo-server-deploy.yml

@@ -20,13 +20,11 @@ jobs:
       with:
         github_access_token: ${{ secrets.GITHUB_TOKEN }}
 
-    - name: Setup SSH key
-      uses: webfactory/ssh-agent@v0.9.0
+    - name: Install SSH Key
+      uses: shimataro/ssh-key-action@v2
       with:
-        ssh-private-key: ${{ secrets.DEMO_SERVER_SSH_KEY }}
-
-    - name: Add server to known hosts
-      run: ssh-keyscan -H ${{ env.SERVER_IP }} >> ~/.ssh/known_hosts
+        key: ${{ secrets.DEMO_SERVER_SSH_KEY }}
+        known_hosts: ${{ secrets.DEMO_SERVER_KNOWN_HOSTS }}
 
     - name: Deploy to demo server
       run: |