Bump github.com/golang/protobuf from 1.4.3 to 1.5.1

Bumps [github.com/golang/protobuf](https://github.com/golang/protobuf) from 1.4.3 to 1.5.1.
- [Release notes](https://github.com/golang/protobuf/releases)
- [Commits](golang/protobuf@v1.4.3...v1.5.1)

Signed-off-by: dependabot[bot] <support@github.com>

go.mod

@@ -11,7 +11,7 @@ require (
 	github.com/getkin/kin-openapi v0.14.0
 	github.com/go-chi/chi v4.0.2+incompatible
 	github.com/go-ozzo/ozzo-validation v3.6.0+incompatible
-	github.com/golang/protobuf v1.4.3
+	github.com/golang/protobuf v1.5.1
 	github.com/gorilla/websocket v1.4.2
 	github.com/lann/builder v0.0.0-20180802200727-47ae307949d0
 	github.com/lib/pq v1.9.0