Bump github.com/golang/protobuf from 1.5.2 to 1.5.3

Bumps [github.com/golang/protobuf](https://github.com/golang/protobuf) from 1.5.2 to 1.5.3.
- [Release notes](https://github.com/golang/protobuf/releases)
- [Commits](golang/protobuf@v1.5.2...v1.5.3)

---
updated-dependencies:
- dependency-name: github.com/golang/protobuf
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

go.mod

@@ -4,7 +4,7 @@ go 1.12
 
 require (
 	github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b
-	github.com/golang/protobuf v1.5.2
+	github.com/golang/protobuf v1.5.3
 	github.com/livepeer/joy4 v0.1.2-0.20191121080656-b2fea45cbded
 	github.com/livepeer/m3u8 v0.11.1
 	github.com/stretchr/testify v1.3.0

go.sum

@@ -3,8 +3,8 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b h1:VKtxabqXZkF25pY9ekfRL6a582T4P37/31XEstQ5p58=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
-github.com/golang/protobuf v1.5.2 h1:ROPKBNFfQgOUMifHyP+KYbvpjbdoFNs+aK7DXlji0Tw=
-github.com/golang/protobuf v1.5.2/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
+github.com/golang/protobuf v1.5.3 h1:KhyjKVUg7Usr/dYsdSqoFveMYd5ko72D+zANwlG1mmg=
+github.com/golang/protobuf v1.5.3/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
 github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/livepeer/joy4 v0.1.2-0.20191121080656-b2fea45cbded h1:ZQlvR5RB4nfT+cOQee+WqmaDOgGtP2oDMhcVvR4L0yA=