Update Inventory Notifications Settings
Updates inventory notification settings.
* `channel_id` can be used as a query parameter to get inventory notification settings per channel. If omitted, you will interact with the global settings only.
* Supplying `null` settings values per channel will delete overrides per given channel and values will be inherited from global level.
* Partial updates are not supported within the given endpoint. In order to delete overrides per channel, `null` should be supplied for all the settings within the given endpoint.