Update tonic requirement from 0.11.0 to 0.12.0 in /hello-grpc-rust

Updates the requirements on [tonic](https://github.com/hyperium/tonic) to permit the latest version.
- [Release notes](https://github.com/hyperium/tonic/releases)
- [Changelog](https://github.com/hyperium/tonic/blob/master/CHANGELOG.md)
- [Commits](hyperium/tonic@v0.11.0...v0.12.0)

---
updated-dependencies:
- dependency-name: tonic
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

hello-grpc-rust/Cargo.toml

@@ -15,7 +15,7 @@ path = "src/landing/client.rs"
 
 [dependencies]
 #grpc https://lib.rs/crates/tonic
-tonic = { version = "0.11.0", features = ["tls"] }
+tonic = { version = "0.12.0", features = ["tls"] }
 #gRPC Codec https://lib.rs/crates/prost
 prost = "0.12.1"
 # https://lib.rs/crates/tokio