Fix Python 3.8 compatibility

app.py

@@ -1,6 +1,5 @@
-from enum import Enum
 from pathlib import Path
-from typing import Hashable
+from typing import Dict, Hashable
 
 import streamlit as st
 import streamlit.components.v1 as components
@@ -222,7 +221,7 @@ def generate(model, inputs, metric, window_len, max_new_tokens):
 def run_context_length_probing(
     _model: GPT2LMHeadModel,
     _tokenizer: PreTrainedTokenizer,
-    _inputs: dict[str, torch.Tensor],
+    _inputs: Dict[str, torch.Tensor],
     window_len: int,
     metric: str,
     generation_mode: bool,