Bump github.com/golang/protobuf from 1.4.2 to 1.4.3

Bumps [github.com/golang/protobuf](https://github.com/golang/protobuf) from 1.4.2 to 1.4.3.
- [Release notes](https://github.com/golang/protobuf/releases)
- [Commits](golang/protobuf@v1.4.2...v1.4.3)

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

Author: dependabot-preview[bot]

go.mod

@@ -10,7 +10,7 @@ require (
 	github.com/go-sql-driver/mysql v1.5.0
 	github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b
 	github.com/golang/mock v1.4.4
-	github.com/golang/protobuf v1.4.2
+	github.com/golang/protobuf v1.4.3
 	github.com/google/certificate-transparency-go v1.1.0 // indirect
 	github.com/google/go-cmp v0.5.2
 	github.com/google/tink/go v1.4.0-rc2

go.sum

@@ -264,6 +264,7 @@ github.com/golang/protobuf v1.4.0/go.mod h1:jodUvKwWbYaEsadDk5Fwe5c77LiNKVO9IDvq
 github.com/golang/protobuf v1.4.1/go.mod h1:U8fpvMrcmy5pZrNK1lt4xCsGvpyWQ/VVv6QDs8UjoX8=
 github.com/golang/protobuf v1.4.2 h1:+Z5KGCizgyZCbGh1KZqA0fcLLkwbsjIzS4aV2v7wJX0=
 github.com/golang/protobuf v1.4.2/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw735rRwI=
+github.com/golang/protobuf v1.4.3/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw735rRwI=
 github.com/golangci/check v0.0.0-20180506172741-cfe4005ccda2/go.mod h1:k9Qvh+8juN+UKMCS/3jFtGICgW8O96FVaZsaxdzDkR4=
 github.com/golangci/dupl v0.0.0-20180902072040-3e9179ac440a/go.mod h1:ryS0uhF+x9jgbj/N71xsEqODy9BN81/GonCZiOzirOk=
 github.com/golangci/errcheck v0.0.0-20181223084120-ef45e06d44b6/go.mod h1:DbHgvLiFKX1Sh2T1w8Q/h4NAI8MHIpzCdnBUDTXU3I0=