Serialization of empty field can create API validation error

[d0rianb]

client-python/zitadel_client/models/user_service_human.py

Lines 81 to 83 in b89a4b8

	# override the default output from pydantic by calling `to_dict()` of email
	if self.email:
	_dict['email'] = self.email.to_dict()

This if checks whether self.email is None, but it does not handle the case where self.email is a UserServiceSetHumanEmail(mail=None).

As a result, the serialization produces email: {} in the request body, and the Zitadel API responds with a 400 error because it expects email to be a valid string between 1 and 200 characters, even though it is null and should remain unchanged.