Merge branch 'fix/mpi-ci-privileges' into 'master'

[ci] advise openmpi to run as root

See merge request !2581

.gitlab-ci/default.yml

@@ -55,6 +55,9 @@ build dumux:
 
 test dumux:
   stage: test
+  variables:
+    OMPI_ALLOW_RUN_AS_ROOT: 1
+    OMPI_ALLOW_RUN_AS_ROOT_CONFIRM: 1
   script:
     - |
       pushd build-cmake