[roll] Roll fuchsia [assembly] Ignore the whole PB directory when checking hermeticity

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1248869
Original-Revision: 85508bae1c540147bae7251db200de55b1440d17
GitOrigin-RevId: aa2edd7fbd79ffbf5cff71f3f5fb2073188b4010
Change-Id: Ic39ca07966f4cb53bf6879b8dc7ea7c61ab5b7d6
diff --git a/stem b/stem
index 51a22d0..6d0925a 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="939e3bfbf9e750e32ae8319341e3e1dcb15a34c9"
+             revision="85508bae1c540147bae7251db200de55b1440d17"
              />
   </projects>
   <hooks>