Rewrite app-config.json without BOM

app-config.json

@@ -1,4 +1,4 @@
-{
+{
   "model_path": "model/best_model.keras",
   "labels": ["Heart", "Oblong", "Oval", "Round", "Square"],
   "port": 7860,
@@ -10,4 +10,4 @@
   "gradio_auth_token": null,
   "gradio_username": null,
   "gradio_password": null
-}
+}