fix(worker): tolerate missing 'payments' key in user.json

Discord users without any past Nitro purchase don't have a 'payments'
field in their user.json export, so user_json['payments'] raises
KeyError. Use .get('payments', []) to skip cleanly.

Author: Androz2091

src/tasks.py

@@ -227,7 +227,7 @@ def read_analytics_file(package_status_id, package_id, link, session):
                 'avatar_url': generate_avatar_url_from_user_id_avatar_hash(relation_ship['id'], relation_ship['user']['avatar']),
                 'display_name': 'display_name' in relation_ship and relation_ship['display_name'] or None,
             })
-        for payment in user_json['payments']:
+        for payment in user_json.get('payments', []):
             payments.append({
                 'id': payment['id'],
                 'amount': payment['amount'],