CI undefined errors in yaml file

As pointed out by @oliver.sander on the mailing list there is an issue with the CI and some yaml files. Some discoveries so far:

• Example of the error (at time of wrtiting): https://gitlab.dune-project.org/core/dune-grid/-/pipelines/28603

• Using CI lint under https://gitlab.dune-project.org/core/dune-grid/-/ci/lint returns a 500 error

• After removing the include part of the yamle file the linting works.

• Linting yaml files of other projects works if they don't have that include part and doesn't if the have this include part.