deps: bump go-grpc (1.23.0) and protobuf (1.3.2) (#1237)

### Release notes

- https://github.com/grpc/grpc-go/releases/tag/v1.23.0
  - much stuff! a bunch of HTTP2-related fixes -- we don't _expose_ go-grpc's listener, but we use it interally all over the place
  - there's `*satus.Is` now: grpc/grpc-go#2868 -- we could make some use of that, I suppose.
  - a bunch of perf improvements, always welcome :)
- https://github.com/golang/protobuf/releases/tag/v1.3.2
  - small fry, but nice stuff: golang/protobuf#785 adds an Unimplemented method to each server, allowing old servers to be used when there's proto changes.

* deps: bump protobuf (1.3.2) and go-grpc (1.23.0)
* deps: bump protobuf (1.3.2) and go-grpc (1.23.0) [revendor]
* deps: bump protobuf (1.3.2) and go-grpc (1.23.0) [regenerate]

Signed-off-by: Stephan Renatus <srenatus@chef.io>

Gopkg.toml

@@ -24,7 +24,7 @@ required = [
 
 [[override]]
   name = "github.com/golang/protobuf"
-  version = "1.3.1"
+  version = "1.3.2"
 
 # "github.com/grpc-ecosystem/go-grpc-middleware" depends on logrus@^1.0.3
 [[override]]
@@ -77,7 +77,7 @@ required = [
 
 [[constraint]]
   name = "google.golang.org/grpc"
-  version = "1.22.0"
+  version = "1.23.0"
 
 [[constraint]]
   name = "github.com/dexidp/dex"