Upgrade the weights loading method to avoid duplicated loading.

app.py

@@ -56,14 +56,16 @@ birefnet.weights_path = weights_path
 def predict(image, resolution, weights_file):
     global birefnet
     if birefnet.weights_path != weights_file:
+        print('*' * 10)
+        print('\t1: ', weights_file, birefnet.weights_path)
         # Load BiRefNet with chosen weights
         _weights_file = '/'.join(('zhengpeng7', usage_to_weights_file[weights_file] if weights_file is not None else 'BiRefNet'))
         print('Change weights to:', _weights_file)
-        print('\t', weights_file, birefnet.weights_path)
         birefnet = birefnet.from_pretrained(_weights_file)
         birefnet.to(device)
         birefnet.eval()
         birefnet.weights_path = weights_file
+        print('\t2: ', weights_file, birefnet.weights_path)
 
     resolution = f"{image.shape[1]}x{image.shape[0]}" if resolution == '' else resolution
     # Image is a RGB numpy array.