[roll] Roll fuchsia [superproject] Roll third_party/pigweed 8e21d97..fd6d1e6 (4 commits)

fd6d1e6 pw_bluetooth_sapphire: Remove emboss CallbackVariant types
b2c1616 pw_stream: Add ReadExact() wrapper
cd0b4fb pw_protobuf_compiler: Don't rely on options file ordering
e35f4d4 docs: Build //docs/* with Bazel

GitOrigin-RevId: daa255f23988205a1a463752d081f0f7dec46680
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1152615
Original-Revision: 902197ae12cbbfddfa376cc678937c459dc04906
Change-Id: I63ca82cb2963c2fef0b07612f5b1b62752c20f03

Author: global-integration-roller

stem

@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="305d6608b0be70aba1ca7ac9d28faac2323ea560"/>
+             revision="902197ae12cbbfddfa376cc678937c459dc04906"/>
   </projects>
   <hooks>
     <hook name="install-environment"