Update PulpCon banner

Author: pedro-psb

custom/main.html

@@ -2,10 +2,10 @@
 
 {# https://squidfunk.github.io/mkdocs-material/setup/setting-up-the-header/#announcement-bar #}
 {% block announce %}
-  🍊 <b>Virtual PulpCon 2025 is coming!</b>
-  Learn more and/or submit a talk
-  <a href="https://discourse.pulpproject.org/t/virtual-pulpcon-2025/2119" target="_blank" rel="noopener noreferrer">
-    here
-  </a>!
+  🍊 <b>Virtual PulpCon 2025 is here (1-3 dec)!</b>
+  Check the
+  <a href="https://hackmd.io/@pulp/pulpcon_2025_schedule" target="_blank" rel="noopener noreferrer">
+    agenda!
+  </a>
   🍊
 {% endblock %}