Change exit code of pylint and unit test scripts
Currently, the scripts running pylint and unit test are returning exit code 0 even if there are errors.
CI needs to parse the log files to understand if there is an error detected or not.
Would be preferred to output a different exit code. It would make CI workflow more straightforward.
Futurize scripts use the "warning" exit code if the script revealed problems in the code and "error" if the script failed to run (wrong setup, no branch,...)