Add ssh key loading debugging

plugin.sh

@@ -26,12 +26,14 @@ generate_secrets() {
 }
 
 load_deploy_key() {
+  echo "--- start ssh key load ---"
   mkdir -p "$HOME/.ssh/"
   ssh-keyscan -p "$PLUGIN_PORT" "$PLUGIN_HOST" > "$HOME/.ssh/known_hosts"
 
   # shellcheck disable=SC2046,SC2006
   eval `ssh-agent`
   echo "$PLUGIN_DEPLOY_KEY" | ssh-add -
+  echo "--- end ssh key load ---"
 }
 
 run_stack_deploy() {