Fix failing test

tests/test_pubmed.py

@@ -5,7 +5,7 @@ from dbxref.retrieve import pubmed
 class TestPubmed(unittest.TestCase):
 
     def test_output(self):
-        documents = pubmed.retrieve([{"db": "Pubmed", "id": "19393038"}], basics=True, references=True, article_ids=True)
+        documents = pubmed.retrieve([{"db": "Pubmed", "id": "19393038"}], basics=True)
         self.assertTrue(documents)