Remove unused imports (#352)

Author: alexhenrie

cloudpickle/cloudpickle.py

@@ -45,7 +45,6 @@
 import abc
 import builtins
 import dis
-from functools import partial
 import io
 import itertools
 import logging
@@ -55,7 +54,6 @@
 import platform
 import struct
 import sys
-import traceback
 import types
 import weakref
 import uuid