Update app.py

app.py

@@ -52,7 +52,7 @@ table = table.head(5)
 
 # Add row with reference model
 row = [reference_model_name] + [50.0] * len(pretty_categories)
-table = table.append(pd.Series(row, index=table.columns), ignore_index=True)
+table = pd.concat([table, pd.DataFrame([pd.Series(row, index=table.columns)])], ignore_index=True)
 table = table.sort_values(by=['Total'], ascending=False) 
 
 table.index = range(1, len(table) + 1)