go: bump github.com/golang/protobuf from 1.4.3 to 1.5.1 in /go

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>

.changelog/3799.internal.md

@@ -0,0 +1 @@
+go: bump github.com/golang/protobuf from 1.4.3 to 1.5.1

go/go.mod

@@ -24,7 +24,7 @@ require (
 	github.com/eapache/channels v1.1.0
 	github.com/fxamacker/cbor/v2 v2.2.1-0.20200820021930-bafca87fa6db
 	github.com/go-kit/kit v0.10.0
-	github.com/golang/protobuf v1.4.3
+	github.com/golang/protobuf v1.5.1
 	github.com/golang/snappy v0.0.3
 	github.com/grpc-ecosystem/go-grpc-middleware v1.2.2
 	github.com/hashicorp/go-hclog v0.15.0
@@ -60,7 +60,7 @@ require (
 	google.golang.org/genproto v0.0.0-20201119123407-9b1e624d6bc4
 	google.golang.org/grpc v1.36.0
 	google.golang.org/grpc/security/advancedtls v0.0.0-20200902210233-8630cac324bf
-	google.golang.org/protobuf v1.25.0
+	google.golang.org/protobuf v1.26.0
 )
 
 go 1.15