[enh] #160: Include examples into the Python package

https://python-poetry.org/docs/pyproject/#include-and-exclude

pyproject.toml

@@ -11,6 +11,7 @@ homepage =  ""
 repository = "https://git.duniter.org/clients/python/duniterpy"
 documentation = "https://clients.duniter.io/python/duniterpy/index.html"
 keywords = ["g1", "duniter", "cryptocurrency", "librecurrency", "library"]
+include = ["examples/*.py"]
 classifiers = [
     "Development Status :: 5 - Production/Stable",
     "Natural Language :: English",