Notification only for cronjob?

I’m developing some software that relies on a library I’m also co-developing. I have set up a cronjob to check my software is still compatible with the latest developments of the library and I’d like to be notified if not. I’ve tried setting up slack notifications, but now we get a notification for every pull-request.

Is there a way to fire email notifications (preferably slack ones) only for jobs run by a cronjob?