[roll] Roll fuchsia [check-licenses] Make allowlist assembly failure fatal

Modify AddAllowlistEntry in allowlist.go to return an error immediately
if builder.Assemble() fails. This prevents the tool from proceeding with
an incomplete configuration, avoiding potential data routing errors or
duplicate entries.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1601857
Original-Revision: be6e01d422239b27b4298d0575675e8bf3714003
GitOrigin-RevId: 053a3276bf303911bda283b9b4d08a669c9db1fe
Change-Id: I59665370c78628b4021ac9f28e44310c795c5116

stem

diff --git a/stem b/stem
index 8910241..56b9416 100644
--- a/stem
+++ b/stem
@@ -8,6 +8,6 @@
             manifest="manifests/platform"
             root=""
             remote="https://fuchsia.googlesource.com/fuchsia"
-            revision="986529f0fb7ba8f472af68373482c257f77a1e8a"/>
+            revision="be6e01d422239b27b4298d0575675e8bf3714003"/>
   </imports>
 </manifest>