change slightly the pipeline script to only attempt to compile latex if the...

change slightly the pipeline script to only attempt to compile latex if the previous doxygen stage worked without errors

.gitlab-ci.yml

@@ -46,10 +46,8 @@ building_stage:
       - cat /etc/os-release
       - cd src
       - echo "Running make ..."
-      - make
-      - make docs
-      - cd ../doc/build/latex
-      - make 
+      - make -j
+      - make docs -j && make -C ../doc/build/latex -j
 
 running_stage:
    stage: run