bpo-36820: Break unnecessary cycle in socket.py, codeop.py and dyld.py (GH-13135)


Break cycle generated when saving an exception in socket.py, codeop.py and dyld.py as they keep alive not only the exception but user objects through the ``__traceback__`` attribute.

https://bugs.python.org/issue36820

Automerge-Triggered-By: @pablogsal
(cherry picked from commit b64334cb93d0ddbb551c8cd712942bab2fc72772)

Co-authored-by: Mario Corchero <mcorcherojim@bloomberg.net>