Change python release scripts to run with Python 3

The release script https://github.com/jbosstm/narayana/blob/master/narayana-release-process.sh (on release process see https://github.com/jbosstm/narayana/wiki/Narayana-Release-Process) uses Python scripts which verifies status of CI and process some other checks.

The current python scripts requires Python in version `2`. The scripts need to be changed to be runnable on Python 3 (maybe we don't need for them being runnable on Python 2 at `master` branch at all).

All Python scripts needs to be verified (at https://github.com/jbosstm/narayana/tree/master/scripts/release) but in particular the `/scripts/release/pre_release.py` fails on Python 3.