[roll] Roll third_party/pigweed c839cb6..b7fb6ab (2 commits)

b7fb6ab:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/155392 SEED-0106: Claim SEED number
7834d83:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/133290 pw_sys_io: Add facade constraint_setting, docs
GitOrigin-RevId: c21e24c7cd47ca20b6b08f1e08d4ecaad9d2558e
Change-Id: I37af81da711777693ae4c3d075a05fd85ee04575
diff --git a/third_party/flower b/third_party/flower
index 2d4f15e..faa914b 100644
--- a/third_party/flower
+++ b/third_party/flower
@@ -451,7 +451,7 @@
              path="third_party/pigweed/src"
              remote="https://pigweed.googlesource.com/pigweed/pigweed"
              gerrithost="https://pigweed-review.googlesource.com"
-             revision="c839cb688a23dafce7dd8446423fa758bca90ace"/>
+             revision="b7fb6ab2b7b0b9b36e81cb3d9ba6b55e41624ebc"/>
     <project name="third_party/github.com/google/python_portpicker"
              gitsubmoduleof="fuchsia"
              path="third_party/python_portpicker/src"