feat: run GNU testsuite

[garasubo]

Fix #5

Added CI to run GNU testsuite for this project

[jmr]

This is useful info, but having this check fail on every commit is suboptimal. Should the failures be compared to a list of expected failures? Is there a finer-grained way to control the tests run?

[garasubo]

@jmr Thank you for your review!

having this check fail on every commit is suboptimal.

I agree. uutils/coreutils repository has a similar CI.
It uploads a reference report file as a github artifact, and compare the current test result against it to detect new failures. This way, the check doesn't fail on every commit.

I can implement a similar approach here if that sounds good to you.

[jmr]

I can implement a similar approach here if that sounds good to you.

FWIW (nothing), SGTM.

I hope some form of this can get merged. It already pointed out missing features (#528). Now, if we could get some PRs reviewed/merged...