Implement monitoring for the mypy wheel build

[JukkaL]

I think that at least two mypy releases have been delayed because the mypy wheel build (https://github.com/mypyc/mypy_mypyc-wheels) was broken and nobody noticed it for some time. It would be great if anybody interested in the health of the build could sign up to receive email notifications about build failures.

This blog post may be relevant (not sure though): https://ravgeetdhillon.medium.com/send-an-email-notification-when-github-actions-fails-ea83cbeabbe0

Steps:

1. Figure out a way of allowing people for subscribe to notifications (Google group?)
2. Implement email notifications
3. Break the build on purpose and check that a notification gets sent (both on master and in a release branch)
4. Unbreak the build

It would be great if somebody can look into this. If you need access to the wheels repo, please let me know and I can give you the access you'd need.

[JukkaL]

As a first step, just having a hard coded list of email addresses in the repository would also be okay. If people wish to subscribe, they can send a PR to add their email address.

[A5rocks]

It sounds like you can get an email/notification from github itself without any of this, as long as you are watching the repository:

https://docs.github.com/en/account-and-profile/managing-subscriptions-and-notifications-on-github/setting-up-notifications/configuring-notifications#github-actions-notification-options

(Not sure though)

[JukkaL]

It sounds like you can get an email/notification from github itself without any of this, as long as you are watching the repository

Hmm it turns out I'm getting emails, but they are super noisy so I've been filtering them. I can probably just filter out emails about successful builds, which would solve my original issue (at least for me). Still, it would be nice to only get emails about failing builds, but at least there's a workaround.