Use printf for multi-line compatibility

Author: aduth

.github/workflows/ds-docs-deploy-production.yml

@@ -36,7 +36,7 @@ jobs:
           # it's sensitive, but to make it easier to change without code revisions.
           SSH_HOST_PUBLIC_KEY: ${{ secrets.DESIGN_SYSTEM_PRODUCTION_SSH_PUBLIC_KEY }}
         run: |
-          echo "$SSH_PRIVATE_KEY" > key.pem
+          printf '%s' "$SSH_PRIVATE_KEY" > key.pem
           chmod 600 key.pem
 
           # Write known_hosts with public key for strict key checking