CI: GitHub Actions

[tueda]

Github Actions offer free 20 concurrent jobs , while Travis CI offers 5. Maybe some of the current CI jobs (for example Valgrind-related jobs), or all of them, could be moved from Google (Travis CI backbone) to Microsoft (GitHub Actions backbone), which gives us a speed gain in CI.

It is also possible to automatize generating documentation on GitHub.

[tueda]

Now, travis-ci.org has been shut down...

[tueda]

I have set up GitHub Actions with 2 workflows. Test is for building and testing with measuring code coverage to be uploaded to coveralls.io. Deploy is for building binaries and generating manuals, which will be published to GitHub Releases when the commit has a versioning tag starting with v, for example, v4.2.2 or v5.0.0.

Some notes:

• Currently, many tests fail due to Test failure (Format broken) #412.
• The Deploy workflow contains code to build native Windows binaries but is now disabled because of too many test failures, which need some investigation.
• Binaries are built with Ubuntu 18.04 and macOS 10.15 images, the oldest versions available that hopefully maximize compatibility, but they are deprecated. If we want to release a patch version, it may be good to do it before their deprecation.
  • The Ubuntu 18.04 Actions runner image will begin deprecation on 2022/08/08 and will be fully unsupported by 2023/04/03 actions/runner-images#6002
  • The macOS 10.15 Actions runner image will begin deprecation on 5/31/22 and will be fully unsupported by 12/1/22 for GitHub and ADO actions/runner-images#5583
• To install Ubuntu packages, I found https://github.com/awalsh128/cache-apt-pkgs-action very helpful. Unfortunately, it doesn't work with LaTeX packages: Failing to correctly recover LaTeX packages awalsh128/cache-apt-pkgs-action#57.
• In the old Travis-CI setup, more tests were available: i386 (added in 7c9706c), sanitizers, forcer (added in d659e9e) and clang. Currently, they are not in this GitHub Actions setup.

In the next commit, I will remove the remaining files related to Travis CI and close this issue.