Update app.py

Pip is opencv-python, opencv when importing

app.py

@@ -1,6 +1,6 @@
 from tensorflow.keras.preprocessing.image import load_img, img_to_array
 import numpy as np
-import opencv-python as op
+import opencv as op
 import gradio as gd
 from keras.models import load_model
 model2 = load_model("./my_model.keras")