[roll] Roll fuchsia [bazel] Support python based post processing script.

There are post processing scripts using python3 internally. To make them
skip passing in their own python binary and runfiles,
fuchsia_post_processing_script.bzl will provide python.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1156146
Original-Revision: 955ef74330fbe243c04d4a4d8293c237550116d9
GitOrigin-RevId: 0a8bd9d38bc9c17957d0441f59a45aef7969821e
Change-Id: I0b1ecc4d25eb8f94f11e84e9e1afff6d1eeb7095
diff --git a/stem b/stem
index c09de3d..78e56dc 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="fd647dca00ee3980ce6198f23bc3eb96c1850697"/>
+             revision="955ef74330fbe243c04d4a4d8293c237550116d9"/>
   </projects>
   <hooks>
     <hook name="install-environment"