Update test_symbol.py

Author: isuruf

symengine/tests/test_symbol.py

@@ -9,7 +9,6 @@ def test_symbol():
     assert str(x) != "y"
     assert repr(x) == str(x)
     # Verify the successful use of slots.
-    assert hasattr(x, "__slots__")
     assert not hasattr(x, "__dict__")
     assert not hasattr(x, "__weakref__")
 
@@ -165,6 +164,5 @@ def test_dummy():
     assert Dummy() != Dummy()
     assert Dummy('x') != Dummy('x')
     # Verify the successful use of slots.
-    assert hasattr(xdummy1, "__slots__")
     assert not hasattr(xdummy1, "__dict__")
     assert not hasattr(xdummy1, "__weakref__")