Depends on deprecated / unmaintained node-slackr #24
Description
This addon notifies Slack by way of node-slackr, which has not been updated since mid-2018. The readme indicates it was deprecated at that point, and points to using the official Slack SDK instead.
node-slackr also has a dependency on request which has been fully deprecated for some time and has a known vulnerability (though I will concede it's unlikely that vulnerability would have an effect on a typical use case here).