Update app.py

app.py

@@ -1,5 +1,9 @@
 import os 
-os.system('pip install detectron2 -f https://dl.fbaipublicfiles.com/detectron2/wheels/cu102/torch1.9/index.html')
+try:
+    import detectron2
+except:
+    import os 
+    os.system('pip install git+https://github.com/facebookresearch/detectron2.git')
 import gradio as gr
 import torch
 import cv2