Update app.py

already a string

app.py

@@ -120,7 +120,7 @@ def add_new_eval(
         "precision": precision,
         "status": "PENDING",
         "submitted_time": current_time,
-        "task": task.str.lower().replace(' ','_'),
+        "task": task.lower().replace(' ','_'),
         "likes": model_info.likes,
         "params": model_size}
         #"license": license,