Update prost-build requirement from =0.13.3 to =0.13.4 (#6860)

Updates the requirements on [prost-build](https://github.com/tokio-rs/prost) to permit the latest version.
- [Release notes](https://github.com/tokio-rs/prost/releases)
- [Changelog](https://github.com/tokio-rs/prost/blob/master/CHANGELOG.md)
- [Commits](tokio-rs/prost@v0.13.3...v0.13.4)

---
updated-dependencies:
- dependency-name: prost-build
  dependency-type: direct:production
...

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

arrow-flight/gen/Cargo.toml

@@ -32,5 +32,5 @@ publish = false
 [dependencies]
 # Pin specific version of the tonic-build dependencies to avoid auto-generated
 # (and checked in) arrow.flight.protocol.rs from changing
-prost-build = { version = "=0.13.3", default-features = false }
+prost-build = { version = "=0.13.4", default-features = false }
 tonic-build = { version = "=0.12.3", default-features = false, features = ["transport", "prost"] }