py312: skip a test that fails with python 3.12

Author: tornaria

src/sage/cpython/debug.pyx

@@ -78,7 +78,7 @@ def getattr_debug(obj, name, default=_no_default):
 
     EXAMPLES::
 
-        sage: _ = getattr_debug(list, "reverse")
+        sage: _ = getattr_debug(list, "reverse")  # not tested - broken in python 3.12
         getattr_debug(obj=<class 'list'>, name='reverse'):
           type(obj) = <class 'type'>
           object has __dict__ slot (<class 'dict'>)