Fix DuniterPy dependency version
Only for DuniterPy for now as it is very coupled:
- [Pipenv dependencies version management](https://pipenv.readthedocs.io/en/latest/basics/#specifying-versions-of-a-package)
- [pip/setup.py dependencies version management](https://stackoverflow.com/questions/8161617/how-can-i-specify-library-versions-in-setup-py)
If breaking change occurs, the installation from `pip` will install latest DuniterPy version and may break Silkaj usage.
issue