Have Make tasks run in parallel using a matrix configuration
Have Make tasks run in parallel using a matrix configuration

It'd be nice if GitHub Actions supported a global before each step, or YAML
anchors, but it doesn't. Instead, a matrix will have to do for getting jobs to
run in parallel with a shared setup phase.

alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf