[ci] add job for doxygen docu build

.gitlab-ci.yml

@@ -113,6 +113,7 @@ full-dune-master-gcc-cpp-20:
     IMAGE: $IMAGE_REGISTRY_URL/full:dune-master-gcc-ubuntu-22.04
     CXX_MAX_STANDARD: "20"
     DUMUX_ENABLE_CPPCHECK: "true"
+    DUMUX_ENABLE_DOXYGEN_BUILD: "true"
 
 ##################################
 # additional scheduled pipelines #

.gitlab-ci/default.yml

@@ -23,6 +23,7 @@ variables:
   REFERENCE_SHA: ""
   CXX_MAX_STANDARD: "17"
   DUMUX_ENABLE_CPPCHECK: ""
+  DUMUX_ENABLE_DOXYGEN_BUILD: ""
 
 
 configure:
@@ -142,6 +143,22 @@ select tests:
       artifacts: true
 
 
+doxygen:
+  stage: build
+  rules:
+  - if: $DUMUX_ENABLE_DOXYGEN_BUILD == "true"
+    when: always
+  script:
+    - cd build-cmake
+    - make doxygen_dumux
+  needs:
+    - job: configure
+      artifacts: true
+  artifacts:
+    paths:
+      - build-cmake/doc/doxygen
+
+
 compile cpp:
   stage: build
   script: