The new PHASE argument can be build, test, or all. all is the default.
This way, the CI/CD script can differentiate between the build and test
phases to make it easier to track down errors when they happen.
The CI/CD workflow will only execute on Ubuntu and MacOS latest version.
The workflow will attempt to build with autotools and CMake and execute
the tests. The workflow will run for all pull requests and pushes done
to the master branch.
