- Add py3-jsonschema and py3-attrs to depends
  (py3-jsonschema is no longer a dependency of poetry since 1.7.0,
   and in that case is wrongly a part of makedepends anyway;
   py3-attrs is listed under "Requirements" in README.md)

- Apply https://git.duniter.org/clients/python/duniterpy/-/commit/5dbf13c6
  to fix compatibility with new poetry

- Apply relevant parts of
  https://git.duniter.org/clients/python/duniterpy/-/commit/ad8f6a26
  to fix compatibility with new py3-libnacl