[roll third_party/pigweed] roll: go

From: version:2@1.21.5
To: version:2@1.21.6
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/187972
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 9640cdef100f87d..9ad961bb7bbd376
Roller-URL: https://ci.chromium.org/b/8758756548545698129
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Iec565e51d9f3d6f99d69d86ce50823b0c4f82b98
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/kudzu/+/187990
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 9640cde..9ad961b 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 9640cdef100f87d7987875d3a418931d6500e5b2
+Subproject commit 9ad961bb7bbd3767c4b0798f2c9553413fc962a2