unable to import gitpython in python

I am using python 3.6.5 and i have installed the gitpython on using pip. After the installation i have tried to import that but i am unable to import this library. Getting below error:

Python 3.6.5 (v3.6.5:f59c0932b4, Mar 28 2018, 17:00:18) [MSC v.1900 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from git import Repo
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Program Files\Python36\lib\site-packages\git\__init__.py", line 8, in <module>
    from git.exc import *                       # @NoMove @IgnorePep8
  File "C:\Program Files\Python36\lib\site-packages\git\exc.py", line 10, in <module>
    from git.compat import safe_decode
  File "C:\Program Files\Python36\lib\site-packages\git\compat.py", line 32, in <module>
    from git.types import TBD
  File "C:\Program Files\Python36\lib\site-packages\git\types.py", line 12, in <module>
    from typing_extensions import Final, Literal, SupportsIndex  # noqa: F401
ImportError: cannot import name 'SupportsIndex'

how to resolve this issue?