Update app.py

app.py

@@ -101,7 +101,7 @@ with gr.Blocks() as demo:
         3. Click **'Get My Certificate'** to check your score and download your certificate.
         """)
     gr.Markdown("---")
-    gr.Markdown("📝 **Note**: You must have completed <a href="http://hf.co/learn/agents-course/unit4/introduction">Unit 4</a> and your Agent must have scored **above 45** to get your certificate.")
+    gr.Markdown("📝 **Note**: You must have completed [Unit 4](https://huggingface.co/learn/agents-course/unit4/introduction) and your Agent must have scored **above 45** to get your certificate.")
 
     gr.LoginButton()
     with gr.Row():