add list_dupes stub

src/main.py

@@ -17,6 +17,11 @@ def main(main_dir: Path, new: Path):
 
     generate_photo_dict(main_dir, main_files, new)
 
+    list_dupes(main_files, new)
+
+def list_dupes(main_files: dict, new:Path):
+    pass
+
 
 def generate_photo_dict(path: Path, file_list: dict, exclude: Path):
     if not path.is_dir():