### Use proper libraries: `hashlib.sha256` stdlib and `base58` - [x] Remove Base58 code, use [`base58` Python module](https://pypi.org/project/base58/) - [x] Add `base58` as a direct dependency to Silkaj? It is already a dependency of DuniterPy. Silkaj will still use DuniterPy and DuniterPy will still use `base58`. Should allow to not have to remove `base58` from Silkaj's `pyproject.toml` when `base58` is not longer directly used. - [x] Remove direct `PyNaCl` dependency from Poetry and the `README.md`. - [x] Instead, use `sha256` from [`hashlib` stdlib](https://docs.python.org/3/library/hashlib.html)