need to add newline to end of private key file

.github/workflows/deploy.yml

@@ -20,12 +20,15 @@ jobs:
           tags: tag:ci
       - name: Add SSH key
         env:
-          SSH_KEY: ${{ secrets.SSH_PRIVATE_KEY }}
+          SSH_PRIVATE_KEY: ${{ secrets.SSH_PRIVATE_KEY }}
         run: |
           mkdir -p ~/.ssh
           MACHINE_IP="$(tailscale ip -4 $MACHINE)"
           ssh-keyscan $MACHINE_IP >> ~/.ssh/known_hosts
-          printf "%s" "$SSH_KEY" > ~/.ssh/key
+          printf "%s" "$SSH_PRIVATE_KEY" > ~/.ssh/key
+          # add a new line to the end of the private key file
+          # otherwise it won't be loaded properly
+          echo >> ~/.ssh/key
           chmod 600 ~/.ssh/key
       - name: Deploy website
         run: |