Replace importlib_metadata with importlib.metadata on Python 3.8+
As of Python3.8 importlib.metadata is the part of stdlib: https://docs.python.org/3/whatsnew/3.8.html#new-modules
Edited by Daniel Pizetta
As of Python3.8 importlib.metadata is the part of stdlib: https://docs.python.org/3/whatsnew/3.8.html#new-modules