Fix VimPathFinder.find_spec (Python 3.4+)

This implements the correct interface for a path entry finder.

Ref: https://docs.python.org/3.8/glossary.html#term-path-entry-finder

Author: blueyed

neovim/plugin/script_host.py

@@ -242,9 +242,9 @@ def find_module(fullname, path=None):
                 return None
 
         @staticmethod
-        def find_spec(fullname, path=None, target=None):
+        def find_spec(fullname, target=None):
             """Method for Python 3.4+."""
-            return PathFinder.find_spec(fullname, path or _get_paths(), target)
+            return PathFinder.find_spec(fullname, _get_paths(), target)
 
     def hook(path):
         if path == nvim.VIM_SPECIAL_PATH: