Traceback (most recent call last):
  File "server.py", line 2, in <module>
    from telegram.ext import Updater
  File "/usr/local/lib/python3.7/dist-packages/telegram/__init__.py", line 23, in <module>
    from .user import User
  File "/usr/local/lib/python3.7/dist-packages/telegram/user.py", line 23, in <module>
    from telegram.utils.helpers import mention_html as util_mention_html
  File "/usr/local/lib/python3.7/dist-packages/telegram/utils/helpers.py", line 93, in <module>
    reference_timestamp: float = None, tzinfo: pytz.BaseTzInfo = None) -> float:
AttributeError: module 'pytz' has no attribute 'BaseTzInfo'