Update .gitlab-ci.yml file with pylint-exit

.gitlab-ci.yml

@@ -7,7 +7,8 @@ pylint:
   stage: test
   script:
     - pip install pylint
-    - pylint --fail-under=9 pydtnsim examples
+    - pip install pylint-exit
+    - pylint pydtnsim examples || pylint-exit $?
 
 pycodestyle:
   stage: test