Bump third_party/nanopb/repo from ab19ecb to 09a3560 (#28405)

Bumps [third_party/nanopb/repo](https://github.com/nanopb/nanopb) from `ab19ecb` to `09a3560`.
- [Commits](nanopb/nanopb@ab19ecb...09a3560)

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

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