Patch an alert's enabled state

Example response

{
  "data": {
    "id": "alt_xyz789",
    "interval": "5m",
    "channels": [
      {
        "type": "webhook",
        "name": "Slack Ops",
        "config": {
          "url": "https://hooks.slack.com/services/T00/B00/xxx"
        }
      }
    ]
  }
}