New `reason` field in subscription canceled webhooks

When a user churns from monday.com, their app subscriptions are also canceled. Therefore, the app_subscription_cancelled webhook will now contain a reason field indicating their subscription was canceled upon renewal. Currently, this is the only instance when the reason field appears, though we plan on adding support for additional reasons in the future.

{
  "type":"app_subscription_cancelled",
  "data":{
    "app_id":1000000000,
    "user_id":1,
    "user_email":"[email protected]",
    "user_name": "User 1",
    "user_cluster": 'other',
    "account_tier": 'free',
    "account_name": "Demo Account",
    "account_slug": "test",
    "account_max_users": 10000,
    "account_id":777777,
    "version_data":{
      "major":1,
      "minor":2,
      "patch":0,
      "type":"minor"
    },
    "timestamp":"2022-06-23T00:00:00.000+00:00",
    "subscription":{
      "plan_id":"plan1",
      "renewal_date":"2022-07-19T00:00:00+00:00",
      "is_trial":false,
      "billing_period":"monthly",
      "days_left":26,
      "pricing_version":5
    },
    "reason":"monday_subscription_cancel_on_renewal"
  }
}