workos.webhooks.constructEvent does not support `flag.created` event, webhook events revoked

[leecjohnny]

SDK event de-serializer: https://github.com/workos/workos-node/blob/b6023aa3296dd0dc508e5bfeb917cad5b0e823e6/src/common/serializers/event.serializer.ts#L26

flag.created is not a case, which leads to the constructEvent to return undefined

In the undefined case, our web hook consumer will revoke the webhook event.

similar to previously resolved issue: https://github.com/workos/workos-node/issues/1360