fix(test): use get_field("author") matching accessor convention

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: LittleCoinCoin

tests/test_package_validator_for_v2_0_0.py

@@ -33,7 +33,7 @@ def test_authors_array_access(self):
 
         service = PackageService()
         service.load_metadata(metadata)
-        authors = service.get_field("authors")
+        authors = service.get_field("author")
         self.assertIsInstance(authors, list)
         self.assertEqual(len(authors), 2)
         self.assertEqual(authors[0]["name"], "Author One")