[roll third_party/pigweed] pw_snapshot: add UUID constants

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/54361

third_party/pigweed Rolled-Commits: 1fee0f44db2d8cf..6cfcd7f0abedad8
Roller-URL: https://ci.chromium.org/b/8840894624690123808
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8840894624690123808
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I4277354d4d1da23e1c8090d0c097ccb75ab3cc82
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/54401
Reviewed-by: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 1fee0f4..6cfcd7f 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 1fee0f44db2d8cf147cc0b4aa87e03a494673110
+Subproject commit 6cfcd7f0abedad85d15a94f619987c9f28afbc06