fix: Make sure we only get valid dirs out of the month directory

bin/archiver.py

@@ -62,7 +62,7 @@ class Archiver(AbstractManager):
         self.logger.debug(f'Updating index for {root_dir}')
         index_file = root_dir / 'index'
         existing_captures_names = {existing_capture.name for existing_capture in root_dir.iterdir()
-                                   if existing_capture.name != 'index'}
+                                   if existing_capture.is_dir()}
         if index_file.exists():
             # Skip index if the directory has been archived.
             try: