[roll] Roll fuchsia [ui] Route fuchsia.ui.display.color.Convertor to session manager

Route the protocol from scenic to session manager so that it becomes
available in session. This protocol will then be routed from
session to android_aidl_graphics_composer in a follow up CL

Original-Bug: b/474649872
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1501916
Original-Revision: a738af3860a1d2db106c8a3a9af15b743a587e9c
GitOrigin-RevId: 034afea519bded3d38458e7b346464710dde0658
Change-Id: I28d51c272599f2af5e08197885a555c466aeb875

stem

diff --git a/stem b/stem
index e03813a..9b9d59e 100644
--- a/stem
+++ b/stem
@@ -8,6 +8,6 @@
             manifest="manifests/platform"
             root=""
             remote="https://fuchsia.googlesource.com/fuchsia"
-            revision="642a7cad92ba4ba8bc3491f7cccd49a24573d3ab"/>
+            revision="a738af3860a1d2db106c8a3a9af15b743a587e9c"/>
   </imports>
 </manifest>