Bump third_party/pigweed/repo from 8ffdd15 to bf2e156

Bumps [third_party/pigweed/repo](https://github.com/google/pigweed) from `8ffdd15` to `bf2e156`.
- [Commits](google/pigweed@8ffdd15...bf2e156)

---
updated-dependencies:
- dependency-name: third_party/pigweed/repo
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

third_party/pigweed/repo

@@ -0,0 +1 @@
+bf2e1563e54b40df91cadf29d27d4ef247762983