Revert "[!40] Switch dune-alugrid in PDELab dependency image to version with fix for Clang 7"
This reverts merge request !40 (merged) and closes #6 (closed). Upstream has fixed the problem in dune-alugrid.
This reverts merge request !40 (merged) and closes #6 (closed). Upstream has fixed the problem in dune-alugrid.