[roll] Roll fuchsia [scenic][ui-input] UI observation fidl

Included in build with:
$ fx set ... --with sdk/fidl/fuchsia.ui.observation,sdk/fidl/fuchsia.ui.observation.test

Original-Bug: 78657
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/542468
Original-Revision: 3abbbb9e9b0c20837e04dbace13ad4bbea7d3871
GitOrigin-RevId: 86efba1568cd8cb210c7c6a0448737ed51b3392d
Change-Id: I6584198cf84506c42d4ec3f27caa9dc68f9e74ad
diff --git a/stem b/stem
index d4aecd3..d790354 100644
--- a/stem
+++ b/stem
@@ -10,7 +10,7 @@
              githooks=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="0a6a1037a352da59fe394876788b120b74c5d2f8"/>
+             revision="3abbbb9e9b0c20837e04dbace13ad4bbea7d3871"/>
   </projects>
   <hooks>
     <hook name="install-environment"