Remove Python 2 compatibility in _compat.NullFinder.

Author: jaraco

importlib_metadata/_compat.py

@@ -56,14 +56,6 @@ class NullFinder:
     def find_spec(*args, **kwargs):
         return None
 
-    # In Python 2, the import system requires finders
-    # to have a find_module() method, but this usage
-    # is deprecated in Python 3 in favor of find_spec().
-    # For the purposes of this finder (i.e. being present
-    # on sys.meta_path but having no other import
-    # system functionality), the two methods are identical.
-    find_module = find_spec
-
 
 def pypy_partial(val):
     """