Merge branch 'fix/headercheck-for-3.4' into 'releases/3.4'

fix headercheck for the dumux folder

See merge request !2760

(cherry picked from commit edce36d9)

ed561229 fix headercheck for the dumux folder
ec7c98bb [examples] include required header
5 jobs for !2761 with cherry-pick-edce36d9
latest merge request