Bump google.golang.org/grpc in /grpc/examples/go/greeter/models (#8130)

Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.53.0 to 1.56.3.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](grpc/grpc-go@v1.53.0...v1.56.3)

---
updated-dependencies:
- dependency-name: google.golang.org/grpc
  dependency-type: direct:production
...

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

grpc/examples/go/greeter/models/go.mod

@@ -3,6 +3,6 @@ module github.com/google/flatbuffers/grpc/examples/go/greeter/models
 go 1.15
 
 require (
-	github.com/google/flatbuffers v1.12.0
-	google.golang.org/grpc v1.53.0
+	github.com/google/flatbuffers v2.0.8+incompatible
+	google.golang.org/grpc v1.56.3
 )