Update gitlab-ci.

3 jobs for feature/update-gitlab-ci in 7 minutes and 35 seconds (queued for 1 second)
Status Name Job ID Coverage
  Test
passed dune:git clang C++17 #29040

00:07:35

passed dune:git gcc-6 C++14 #29042

00:05:08

passed dune:git gcc-8 C++17 #29041

00:06:29