text: Title: Code  execute raise TypeError: 'PandasConnector' object is not subscriptable, looks PandasConnector not be well linked to a DataFrame.
  Body: ### System Info
  
  pandasai==2.0.21
  pytho==3.9.19
  os==ubuntu
  
  ### 🐛 Describe the bug
  
  The bug is PandasConnector isn't well-linked to a Pandas Dataframe, as error message below, running generated code to manipulate df raise error.
  
  The user asked the following question:
  QUERY
   德州仪器中工作温度相同的芯片有哪些
  
  You generated this python code:
  import pandas as pd
  
  Assuming the DataFrame provided is already given to us as df.
  df = dfs[0]
  
  Filter the DataFrame for Texas Instruments
  texas_instruments_df = df[df['制造商'] == 'Texas Instruments']
  
  Ensure that we only consider rows where temperature values are not NaN
  texas_instruments_df = texas_instruments_df.dropna(subset=['最小工作温度', '最大工作温度'])
  
  Group by unique combinations of minimum and maximum working temperature
  grouped_by_temp_df = texas_instruments_df.groupby(['最小工作温度', '最大工作温度'])
  
  Extract groups with more than one entry (the same working temperature range)
  common_temp_chips = {}
  for (min_temp, max_temp), group in grouped_by_temp_df:
      if len(group) > 1:
          common_temp_chips[f"{min_temp}C to {max_temp}C"] = group['零件型号'].tolist()
  
  Convert dictionary to DataFrame for better readability
  common_temp_chips_df = pd.DataFrame([(k, v) for k, v in common_temp_chips.items()], columns=['Temperature Range', 'Chip Models'])
  
  Showing the result
  print(common_temp_chips_df)
  
  It fails with the following error:
  Traceback (most recent call last):
    File "/root/anaconda3/envs/chatdb/lib/python3.9/site-packages/pandasai/pipelines/chat/code_execution.py", line 64, in execute
      result = code_manager.execute_code(code_to_run, code_context)
    File "/root/anaconda3/envs/chatdb/lib/python3.9/site-packages/pandasai/helpers/code_manager.py", line 182, in execute_code
      code_to_run = self._clean_code(code, context)
    File "/root/anaconda3/envs/chatdb/lib/python3.9/site-packages/pandasai/helpers/code_manager.py", line 562, in _clean_code
      self._extract_fix_dataframe_redeclarations(node, clean_code_lines)
    File "/root/anaconda3/envs/chatdb/lib/python3.9/site-packages/pandasai/helpers/code_manager.py", line 467, in _extract_fix_dataframe_redeclarations
      exec(code, env)
    File "<string>", line 3, in <module>
  TypeError: 'PandasConnector' object is not subscriptable