Fix protobuf version in the example (#8509)
Fix protobuf version in the example (#8509)

The version variable should be `protobuf_VERSION` in `CMakeLists.txt`.
google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf