update poster for fastml conference 2026

Author: marco66colombo

_data/events.yml

@@ -10,7 +10,7 @@
 - title: "Fast Machine Learning for Science Workshop 2026"
   date: "Aug 31-Sep 4, 2026"
   location: "UC San Diego"
-  image: "/images/fastml_logo.png"
+  image: "/images/fastml_poster_2026.png"
   external_link: "https://indico.cern.ch/event/1654479/"
 
 - title: "Fast Machine Learning for Science Conference 2025"