Update .gitlab-ci.yml file

.gitlab-ci.yml

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