address deprecation of pkgutil.get_loader

Closes #165

Author: wisp3rwind

confuse/util.py

@@ -1,3 +1,4 @@
+import importlib
 import os
 import sys
 import argparse
@@ -115,7 +116,12 @@ def find_package_path(name):
     ``name == "__main__"``).
     """
     # Based on get_root_path from Flask by Armin Ronacher.
-    loader = pkgutil.get_loader(name)
+    try:
+        spec = importlib.util.find_spec(name)
+    except (ImportError, ValueError):
+        return None
+
+    loader = spec.loader
     if loader is None or name == '__main__':
         return None