remove invalid asserts from tuple tests

CPython 3.7 and PyPy 7.1 unify tuples as common constants, like this:
(1, 2) is tuple(1, 2)
CPython 3.6 and GraalPython don't do this optimization and the tests
assume that.
Remove this assumption as it's an implementation detail.

Author: msimacek

graalpython/com.oracle.graal.python.test/src/tests/test_tuple.py

@@ -236,12 +236,10 @@ def __iter__(self):
         t = (2,)
         tt = tuple((2,))
         self.assertEqual(t,tt)
-        self.assertFalse(t is tt)
 
         ttt = tuple(t)
         self.assertEqual(t,ttt)
         self.assertEqual(tt,ttt)
-        self.assertFalse(ttt is tt)
         self.assertTrue(ttt is t)
 
         m = MyTuple((2,))