Fix class test for rpy2 3.4

Change-Id: Ice09b3ceec97a2fc2740c85000b7d89cb36a1438
diff --git a/KorAPClient/tests/test_korapclient.py b/KorAPClient/tests/test_korapclient.py
index 34a52fa..6e25013 100644
--- a/KorAPClient/tests/test_korapclient.py
+++ b/KorAPClient/tests/test_korapclient.py
@@ -8,7 +8,7 @@
 
     def test_query(self):
         q = self.kcon.corpusQuery("Test")
-        self.assertEqual(q.slots['class'], 'KorAPQuery')
+        self.assertEqual(q.slots['class'][0], 'KorAPQuery')
 
     def test_frequency_query(self):
         df = self.kcon.frequencyQuery("Ameisenplage")