Bump protobuf version for Java gRPC sample app

[KaloyanPr]

The current protobuf version for the sample Java gRPC project results in using a protoc that is not available for macOS with Apple Silicon chips. Example errors before updating the version:

I508638@HFJF72M9TP http2 % ./gradlew clean build

> Task :java-grpc:app:generateProto FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':java-grpc:app:generateProto'.
> Could not resolve all files for configuration ':java-grpc:app:protobufToolsLocator_protoc'.
   > Could not find protoc-3.17.2-osx-aarch_64.exe (com.google.protobuf:protoc:3.17.2).
     Searched in the following locations:
         https://repo.maven.apache.org/maven2/com/google/protobuf/protoc/3.17.2/protoc-3.17.2-osx-aarch_64.exe

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

After upgrading the version to the latest supported for this major release -

I508638@HFJF72M9TP http2 % ./gradlew clean build        


BUILD SUCCESSFUL in 3s
18 actionable tasks: 18 executed

As you can see, there is no pre-built binary for the ARM64 architecture - https://repo.maven.apache.org/maven2/com/google/protobuf/protoc/3.17.2/.

[cla-assistant]

All committers have signed the CLA.

[peanball]

Thanks for the contribution!