Remove empty homepage field from pyproject

Since this is breaking Python Poetry based projects
depending on DuniterPy
At least for Silkaj, I get the following

RuntimeError: The Poetry configuration is invalid:
  - data.homepage must be uri

Can be re-added once there would be a website

pyproject.toml

@@ -7,7 +7,6 @@ authors = ["inso <insomniak.fr@gmail.com>", "canercandan", "s_b"]
 maintainers = ["vit <vit@free.fr>", "Moul <moul@moul.re>"]
 readme = "README.md"
 license = "GPL-3.0-or-later"
-homepage =  ""
 repository = "https://git.duniter.org/clients/python/duniterpy"
 documentation = "https://clients.pages.duniter.org/python/duniterpy/index.html"
 urls = { Changelog = "https://git.duniter.org/clients/python/duniterpy/-/blob/main/CHANGELOG.md" }