Fix f-string syntax error in app.py (line 96)

app.py

@@ -93,7 +93,7 @@ def run_dashboard(data_src, ticker, file_upload, timeframe, start_date, end_date
         )
         if isinstance(result, dict) and result.get("error"):
             logging.error(f"Model training failed: {result['error']}")
-            return [None] * 12 + [f"Model training failed: {result["error"]}", None, None, None, None, f"Model training failed: {result["error"]}"]
+            return [None] * 12 + [f"Model training failed: {result['error']}", None, None, None, None, f"Model training failed: {result['error']}"]
 
         signals_df, trades_df, equity_df = generate_signals(df, result)
         if signals_df.empty: