Bump third_party/pigweed/repo from 45b1073 to 4e9bb2b (#27469)

Bumps [third_party/pigweed/repo](https://github.com/google/pigweed) from `45b1073` to `4e9bb2b`.
- [Commits](google/pigweed@45b1073...4e9bb2b)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>