GmshReader deprecation warnings

Using the GmshReader causes a lot of deprecation warnings:

dumux/dumux/io/grid/gridmanager_base.hh:216:45: Warnung: »static void Dune::GmshReader<GridType>::read(Dune::GridFactory<GridType>&, const string&, std::vector<int>&, std::vector<int>&, bool, bool) [with GridType = Dune::FoamGrid<1, 3>; std::string = std::basic_string<char>]« ist veraltet: Deprecated after Dune 2.7 (ca. 2020-02): The insertBoundarySegments argument for this overload of the read method is deprecated, please omit it.  See https://gitlab.dune-project.org/flyspray/FS/issues/1698.  When setting insertBoundarySegments=false there is no way to correctly use the data returned in boundarySegmentToPhysicalEntity, which makes using the old method error-prone. [-Wdeprecated-declarations]
                 Dune::GmshReader<Grid>::read(*gridFactory, fileName, boundaryMarkers, elementMarkers, verbose, boundarySegments);