Fix typo in walrus op that selected the wrong seed!

app.py

@@ -39,7 +39,7 @@ with gr.Blocks(css=".container { max-width: 800px; margin: auto; }") as demo:
         image_with_seed = None
         visible = (False, False)
 
-        if seed_index := state["selected"] > -1:
+        if (seed_index := state["selected"]) > -1:
             seed = state["seeds"][seed_index]
             image_with_seed = infer_seeded_image(prompt, seed)
             visible = (False, True)