Erlang 27 is fully supported in main and v4.1.x. Support for Erlang 26
in v4.1 remains. It's better to "drop" erlang 26 from CI because, at the
moment, our PRs and commits to main trigger about 270 jobs. If we just
add '27' to the matrix, we would spawn ~216 more jobs, totalling around
496 jobs per PR and commit to main. That's simply too much, because it's
reaching the usage limits of Github Actions [1], namely the 256 limit of
matrix jobs.
[1]
https://docs.github.com/en/actions/administering-github-actions/usage-limits-billing-and-administration#usage-limits
Instead of every time we run Make for these applications.
This means that during development we are free to modify
these values or create new test suites without having to
worry about the check. If we forget to then add the test
suites in PARALLEL_CT the workflow will tell us.
This is a proof of concept that mostly works but is missing
some tests, such as rabbitmq_mqtt or rabbitmq_cli. It also
doesn't apply to mixed version testing yet.