Added CI and set 2.8 dune version.

.gitlab-ci.yml

+---
+variables:
+  DUNE_CMAKE_FLAGS:   "-DDUNE_ENABLE_PYTHONBINDINGS=ON -DDUNE_MAX_TEST_CORES=4 -DBUILD_SHARED_LIBS=TRUE -DDUNE_PYTHON_INSTALL_LOCATION=none -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_LATEX=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_Alberta=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_Vc=TRUE -DCMAKE_DISABLE_DOCUMENTATION=TRUE"
+  DUNECI_CMAKE_FLAGS: $DUNE_CMAKE_FLAGS
+  DUNE_CONTROL_PATH:  /duneci/modules:$CI_PROJECT_DIR
+  DUNE_PY_DIR:        /duneci/modules/dune-py
+  # adding this actually leads to the test failure seen in the core modules
+  # don't know why this is required here but not for core modules - magic?
+  DUNECI_PARALLEL:      "6"
+  PYTHONPATH:         "/duneci/modules/dune-common/build-cmake/python:/duneci/modules/dune-geometry/build-cmake/python:/duneci/modules/dune-grid/build-cmake/python:/duneci/modules/dune-istl/build-cmake/python:/duneci/modules/dune-alugrid/build-cmake/python:/duneci/modules/dune-fem/build-cmake/python:$CI_PROJECT_DIR/build-cmake/python"
+
+before_script:
+  - . /duneci/bin/duneci-init-job
+  - duneci-install-module https://gitlab.dune-project.org/core/dune-common.git
+  - duneci-install-module https://gitlab.dune-project.org/core/dune-geometry.git
+  - duneci-install-module https://gitlab.dune-project.org/core/dune-grid.git
+  - duneci-install-module https://gitlab.dune-project.org/extensions/dune-alugrid.git
+
+debian-11-gcc-9-17:
+  image: registry.dune-project.org/docker/ci/debian:11
+  script:
+    - duneci-standard-test
+  variables:
+    DUNECI_TOOLCHAIN:  gcc-9-17
+    DUNE_CMAKE_FLAGS:  "-DDUNE_ENABLE_PYTHONBINDINGS=OFF -DDUNE_MAX_TEST_CORES=4 -DBUILD_SHARED_LIBS=TRUE -DDUNE_PYTHON_INSTALL_LOCATION=none -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_LATEX=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_Alberta=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_Vc=TRUE -DCMAKE_DISABLE_DOCUMENTATION=TRUE"
+
+ubuntu-20.04-gcc-9-17:
+  image: registry.dune-project.org/docker/ci/ubuntu:20.04
+  script:
+    - duneci-standard-test
+  variables:
+    DUNECI_TOOLCHAIN:  gcc-9-17

dune.module

 Module: dune-metagrid
-Version: 2.6.0
-Maintainer: dune@mathematik.uni-freiburg.de
-Depends: dune-grid (>= 2.6) dune-alugrid (>= 2.6)
-Suggests: dune-spgrid (>= 2.6) 
+Version: 2.8-git
+Maintainer: dune-devel@lists.dune-project.org
+Depends: dune-grid (>= 2.8) dune-alugrid (>= 2.8)
+Suggests: dune-spgrid (>= 2.8)