[roll third_party/pigweed] Add Bazel support for pw_rpc/py and deps

Testing: Verified that pw_rpc bazel target builds locally

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/51480

third_party/pigweed Rolled-Commits: 25ce8a26467df3c..6bdcc3fe3380eda
Roller-URL: https://ci.chromium.org/b/8840622320129334720
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8840622320129334720
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I98d4d77c63ed8f1707d8f26e88e454591bea30db
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/54701
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 25ce8a2..6bdcc3f 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 25ce8a26467df3c489fe86cfc7f9523faf3ad137
+Subproject commit 6bdcc3fe3380eda25fecb427108a983b86020867