@All in the mention property of the webhooks

News URL
[Messaging API now includes @All in the mention property of the webhooks](https://developers.line.biz/en/news/2023/03/08/messaging-api-updated/)

see the [Text](https://developers.line.biz/en/reference/messaging-api/#wh-text) section of [Message event](https://developers.line.biz/en/reference/messaging-api/#message-event)