remove leftover utf-8 encode from path handling

Reaving the .encode in the code causes folders with non-ASCII symbols (tested with some German umlauts) to show up empty in "browse".
After removing, the folder contents show up fine.

mopidy/file/library.py

@@ -141,5 +141,5 @@ class FileLibraryProvider(backend.LibraryProvider):
     def _is_in_basedir(self, local_path):
         return any(
             path.is_path_inside_base_dir(
-                local_path, media_dir['path'].encode('utf-8'))
+                local_path, media_dir['path'])
             for media_dir in self._media_dirs)