fix json `np.float32` issue

app.py

@@ -144,7 +144,8 @@ def detect_objects(image, prompt, show_masks=True, show_boxes=True, crop_options
 
         # save object information in json
         res_json["objects"].append(
-            {"label": label, "score": np.max(scores), "box": input_box.tolist(), "center": center_point.tolist(),
+            {"label": label, "score": np.max(scores).item(), "box": input_box.tolist(),
+             "center": center_point.tolist(),
              "avg_size": avg_size})
 
     return [res_json, output_image_paths]