Add .gitlab-ci.yml.

5 jobs for releases/2.4-1
latest
Status Name Job ID Coverage
  Test
passed dune:2.4--clang #390

00:00:22

passed dune:2.4--gcc #389

00:00:24

failed dune:2.4--clang #386

00:00:07

failed dune:2.4--gcc #387

00:00:05

failed dune:2.4--gcc #388

00:00:16