roll: third_party/pigweed 42cff57..8f18755 (4 commits)

8f18755:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/234312 docs: Add fixed point blog
801fb32:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/237972 pw_async2: Refactor Dispatcher to raise top-level API out of CRTP
90d0137:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/216272 bazel: Clean up for-migration-only alias
adbc840:https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/237913 bazel: Update rules_python to v0.36.0

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 42cff573c2016f..8f18755dc9a225
Roller-URL: https://ci.chromium.org/b/8735603066922194881
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ic015c91dd19f48361de3be25d7fa44bf7978df08
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/238633
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.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 42cff57..8f18755 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 42cff573c2016f8d0f78ef2f0db8cd9941601ab4
+Subproject commit 8f18755dc9a225caacf2b190d1114ebfda4a2642