fix: dev: [vps] try to be consistent and allow common parsing by ``0km``.

Signed-off-by: Valentin Lab <valentin.lab@kalysto.org>

bin/vps

@@ -241,7 +241,7 @@ mailcow:install-backup() {
     fi
 
     info "You can run this following from an host having admin access to $dest:"
-    echo "ssh ${ssh_options[@]} myadmin@$dest ssh-key add \"$(cat /var/lib/rsync/.ssh/id_rsa.pub)\""
+    echo "ssh ${ssh_options[@]} myadmin@$dest ssh-key add '$(cat /var/lib/rsync/.ssh/id_rsa.pub)'"
 }
 
 compose:has_domain() {