test_code: skip test_basic

Author: cosminbasca

graalpython/com.oracle.graal.python.test/src/tests/unittest_tags/test_code.txt

@@ -7,3 +7,4 @@
 *graalpython.lib-python.3.test.test_code.CodeTest.test_constructor
 *graalpython.lib-python.3.test.test_code.CodeTest.test_newempty
 *graalpython.lib-python.3.test.test_code.CodeTest.test_replace
+*graalpython.lib-python.3.test.test_code.CodeWeakRefTest.test_basic

graalpython/lib-python/3/test/test_code.py

@@ -319,6 +319,7 @@ def test_interned_string_with_null(self):
 
 class CodeWeakRefTest(unittest.TestCase):
 
+    @cpython_only
     def test_basic(self):
         # Create a code object in a clean environment so that we know we have
         # the only reference to it left.