Bump Go dependencies

• Pick up security fix in Go 1.21.9 - https://groups.google.com/g/golang-announce/c/YgW0sx8mN3M
• Pick up the same security fix in gRPC 1.63.0 - https://github.com/grpc/grpc-go/pull/7082
• NewClient is the new way to create a gRPC client - https://github.com/grpc/grpc-go/pull/7010