Fix indentation in app.py for control_upload_sets enumeration in run_training function, improving code readability and structure.

app.py

@@ -454,7 +454,7 @@ def run_training(
         return
 
     control_dirs: List[Optional[str]] = []
-for i, uploads in enumerate(control_upload_sets):
+    for i, uploads in enumerate(control_upload_sets):
         if not uploads:
             control_dirs.append(None)
             continue