Fix/atrribute error crash when no postal info supplied

[yuriverweij]

Fix AttributeError in Contact.update() when postal_info=None

Problem

Calling Contact.update() with a ContactData where postal_info is None (the default) raised an AttributeError in two places:

1. _data_to_dict() — called .pop("address", {}) directly on postal_info without guarding against None
2. update() — accessed contact.postal_info.address unconditionally when computing address_change

Changes

pyepp/contact.py

• _data_to_dict: guard postal_info.pop(...) with if postal_info is not None
• update: use short-circuit evaluation bool(contact.postal_info and contact.postal_info.address) for address_change

tests/test_contact.py

• Added test_data_to_dict_without_postal_info — verifies _data_to_dict handles postal_info=None without crashing and omits postal fields from the result
• Added test_update_without_postal_info — regression test asserting postalinfo_change=False and address_change=False are passed to execute when postal_info=None
• Strengthened existing test_update to assert postalinfo_change=True is passed to execute

[yuriverweij]

Linting:
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)
All unit tests also pass.

[ehsan-fj]

Great, thanks 🚀