Prefer relative imports for abc.

Author: jaraco

importlib_resources/__init__.py

@@ -17,7 +17,7 @@
     Resource,
 )
 
-from importlib_resources.abc import ResourceReader
+from .abc import ResourceReader
 
 
 __all__ = [

importlib_resources/tests/test_files.py

@@ -2,7 +2,7 @@
 import unittest
 
 import importlib_resources as resources
-from importlib_resources.abc import Traversable
+from ..abc import Traversable
 from . import data01
 from . import util