Clear channel read state

curl --request DELETE \
  --url https://api.fluxer.app/v1/channels/{channel_id}/messages/ack \
  --header 'Authorization: <api-key>'

{
  "code": "ACCESS_DENIED",
  "message": "<string>",
  "errors": [
    {
      "path": "<string>",
      "message": "<string>",
      "code": "<string>"
    }
  ]
}