PDELab tutorials CI are broken

It seems to be some time since the PDELab tutorials are broken in this CI: https://gitlab.dune-project.org/pdelab/dune-pdelab/-/pipelines?page=1&scope=all&ref=master

• The CI does not report an error on configuration failure of the module.
• The error looks like this:

CMake Error at overview/CMakeLists.txt:1 (add_latexmk_document):
  Unknown CMake command "add_latexmk_document".