pylint: fix no-member case

Fix the only case of E1101 no-member.

Part of #270

Author: DifferentialOrange

test/suites/test_schema.py

@@ -131,6 +131,7 @@ def setUpClass(cls):
             box.space.constr_tester_2:create_index('I1', { parts = {'id'} })
             box.space.constr_tester_2:create_index('I2', { parts = {'table1_id'} })
             """)
+        cls.encoding = None
 
     def setUp(self):
         # prevent a remote tarantool from clean our session