Removing unnecesary line in test

There is a line in one of the tests that tries to access a class attribute that doesn't exist. While it isn't breaking in any sense, that line is pointless. I've run the tests without the line that they pass appropiately.

Author: IMC00

exercises/concept/ellens-alien-game/classes_test.py

@@ -144,7 +144,6 @@ def test_alien_class_variable(self):
         """Test class attribute/variables are identical across instances."""
 
         alien_one, alien_two = Alien(0, 2), Alien(-6, -1)
-        Alien.health = 6
 
         created_error_message = ('Created two new Aliens and requested the '
                                  'total_aliens_created attribute for each one. '