Remove assertion for Mujoco viewer close (#334)

This problem is resolved by #340

Author: naeioi

tests/helpers.py

@@ -1,6 +1,5 @@
 import pickle
 
-from tests.quirks import KNOWN_GYM_CLOSE_BROKEN
 from tests.quirks import KNOWN_GYM_RENDER_NOT_IMPLEMENTED
 
 
@@ -43,10 +42,3 @@ def step_env_with_gym_quirks(test_case,
         # Roundtrip serialization
         round_trip = pickle.loads(pickle.dumps(env))
         assert round_trip.env.spec == env.env.spec
-
-    if not spec.id in KNOWN_GYM_CLOSE_BROKEN:
-        env.close()
-    else:
-        with test_case.assertRaisesRegex(
-                AttributeError, "'MjViewer' object has no attribute 'finish'"):
-            env.close()