Bump third_party/pigweed/repo from 90d97fa to fddeb6c

Bumps [third_party/pigweed/repo](https://github.com/google/pigweed) from `90d97fa` to `fddeb6c`.
- [Commits](google/pigweed@90d97fa...fddeb6c)

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

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