Minor bugs in main.py backend-apis

[Ruthvik-1411]

• generate_sql() missing 1 required positional argument: num_sql_matches

  Open_Data_QnA/backend-apis/main.py

  Line 417 in 269f42d

  generated_sql,invalid_response = await generate_sql(user_question,

• ValueError: too many values to unpack (expected 2) in main.py,
  

  Open_Data_QnA/backend-apis/main.py

  Line 417 in 269f42d

  generated_sql,invalid_response = await generate_sql(user_question,

• get_response() missing 1 required postional argument: 'result_df'.

  Open_Data_QnA/backend-apis/main.py

  Line 374 in 269f42d

  result,invalid_response=get_response(user_question,result_df.to_json(orient='records'))