Make sure github CI sends an email on CI build failure

[TheQuantumPhysicist]

Not sending emails about that could make the results invisible to devs.

We have to make it send emails to the relevant developers. Not to everyone. We don't want this to become an annoying spam thing.

[muursh]

I already get emails for this. Am I the only one?

[TheQuantumPhysicist]

Apparently you are! :-)

It's not important now though. We'll get to it at some time.

[altonen]

I also get them but only for the PRs I've submitted