message: Use display name when pinned messages are changed
diff: @@ -473,7 +473,7 @@ function textForPowerEvent(event) {
  }
  function textForPinnedEvent(event) {
  - const senderName = event.getSender();
  + const senderName = event.sender ? event.sender.name : event.getSender();
  return _t("%(senderName)s changed the pinned messages for the room.", {senderName});
  }
  