[roll third_party/pigweed] build: Use rules_python in Bazel build files

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/188690

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 0380161bd68c216..ffc60786179e0c2
Roller-URL: https://ci.chromium.org/b/8758174307826987841
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I62bde5b42b75f9931907c2245243ac3ef647a637
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/188713
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 0380161..ffc6078 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 0380161bd68c216a590230f0cc49d26add7eef8a
+Subproject commit ffc60786179e0c2099ffe2a94f18c12b0e93db46