Use example sites that allow simple scraping

UN site is protected by CloudFront and the fails on simple scraping.

app.py

@@ -147,7 +147,7 @@ g = gr.Interface(
     examples=[
         [
             "Which actions can we take to reduce climate change?",
-            "https://www.un.org/en/actnow/",
+            "https://www.imperial.ac.uk/stories/climate-action/",
         ],
         [
             "Which actions can we take to reduce climate change?",