[Other]Update im.copy() to im in examples (#854)

* Update keypointdetection result docs

* Update im.copy() to im in examples

examples/vision/detection/yolov7/python/infer.py

@@ -52,7 +52,7 @@ if args.image is None:
 else:
     image = args.image
 im = cv2.imread(image)
-result = model.predict(im.copy())
+result = model.predict(im)
 
 # 预测结果可视化
 vis_im = fd.vision.vis_detection(im, result)