[roll third_party/pigweed] pw_env_setup: Update cipd pin

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/38700

third_party/pigweed Rolled-Commits: a1cb66309e3542c..4e6d038872b3a54
Roller-URL: https://ci.chromium.org/b/8851934109186947136
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8851934109186947136
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: If9264f66955556959785e99214eaaee21d68322e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/39163
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 a1cb663..4e6d038 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit a1cb66309e3542c02f9e428fe35c49c83440e2a9
+Subproject commit 4e6d038872b3a54c30a8d383c01ce8c0c4bd18d0