Use the correct path for packaging/version in setuptools

Index: tests/test_rio_main.py
--- tests/test_rio_main.py.orig
+++ tests/test_rio_main.py
@@ -1,7 +1,7 @@
 import logging
 import sys
 
-from packaging.version import parse
+from pkg_resources._vendor.packaging.version import parse
 
 from rasterio.rio.main import main_group