Acknowledge a message

curl --request POST \
  --url https://api.fluxer.app/v1/channels/{channel_id}/messages/{message_id}/ack \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "mention_count": 1073741823,
  "manual": true
}
'

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