Bump prost-build from 0.11.8 to 0.11.9 (#62)

Bumps [prost-build](https://github.com/tokio-rs/prost) from 0.11.8 to 0.11.9.
- [Release notes](https://github.com/tokio-rs/prost/releases)
- [Commits](tokio-rs/prost@v0.11.8...v0.11.9)

---
updated-dependencies:
- dependency-name: prost-build
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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