change backend host

app.py

@@ -43,11 +43,15 @@ def change_image_style(
         "prompt_prefix": prompt_prefix
     }
 
-    response = requests.post(
-        "https://api.hkhappymobile.com/tools/change-image-style",
-        json=data,
-        headers={"content-type": "application/json"}
-    )
+    try:
+        response = requests.post(
+            "http://3.20.241.172/tools/change-image-style",
+            json=data,
+            headers={"content-type": "application/json"}
+        )
+    except Exception as e:
+        error_msg = f"Error occurred while requesting backend tool: {e}"
+        return "", "", error_msg
 
     if response.status_code == 200:
         data = response.json().get("data")