update hilla to 24.9.0-beta2 (#7991)

Author: vaadin-bot

versions.json

@@ -149,7 +149,7 @@
             "npmName": "@vaadin/grid"
         },
         "hilla": {
-            "javaVersion": "24.9.0-beta1"
+            "javaVersion": "24.9.0-beta2"
         },
         "horizontal-layout": {
             "jsVersion": "24.9.0-beta1",