GitHub CI instead of Travis about math

[alexeyshockov]

Also a question to discuss, @BenMorel :) Partially related to other discussions about CI tools that we are doing already.

[BenMorel]

@alexeyshockov I haven't had the time to look into the matter, however at first glance I'm failing to see the real advantage to make the switch: Travis CI works quite well, and I have never run into any kind of time limitation, I'm not even sure there is one in the free version. So this is obviously a plus for Travis.

Do you have a link to another repo integrated with GitHub CI (is it what they call Actions, by the way?) where I could see the benefit of a better integration?

[BenMorel]

I've changed my mind, given that:

• Travis has started removing processing power for open-source projects and builds now take a lot of time to start;
• GitHub Actions do not seem to impose a limit for open-source projects: the 2,000 minutes / month limit seems to only apply to private repos!

This has been taken care of in 8fded77.

The only thing I've not been able to integrate with GitHub Actions is the smoke check. Do you know if this is possible, @alexeyshockov?

[BenMorel]

It is possible, using another job and adding needs: to the main job: c2ed5a6.

I've decided to revert to not using smoke tests, though, as I discovered that by default, GitHub Actions uses a fail-fast strategy, where pending jobs are cancelled if any job fails. This is good enough for us.

Move to GitHub Actions: done ✔️ !