build(deps): update prost-build requirement from 0.11 to 0.12

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)
- [Commits](tokio-rs/prost@prost-build-0.11.1...v0.12.0)

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

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

proto-compiler/Cargo.toml

@@ -10,7 +10,7 @@ publish = false
 
 [dependencies]
 walkdir = { version = "2.3" }
-prost-build = { version = "0.11" }
+prost-build = { version = "0.12" }
 tempfile = { version = "3.2.0" }
 regex = { "version" = "1.7.1" }
 # Use of native-tls-vendored should build vendored openssl, which is required for Alpine build