scripts: use latest gogo/protobuf for proto files
scripts: use latest gogo/protobuf for proto files

As gogo/protobuf was updated to generate grpc.SupportPackageIsVersion3
by default, genproto.sh needs to be also updated.

See also https://github.com/coreos/etcd/pull/5703

coreos/fleet,endocode/fleet,endocode/fleet,coreos/fleet,jonboulle/fleet,dongsupark/fleet,dongsupark/fleet,jonboulle/fleet,giantswarm/fleet,endocode/fleet,jonboulle/fleet,dalbani/fleet,dalbani/fleet,giantswarm/fleet,dongsupark/fleet,dalbani/fleet,giantswarm/fleet,coreos/fleet