fix double ack

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

segmentio.go

@@ -397,7 +397,7 @@ func (h *cgHandler) run(ctx context.Context) {
 				if h.subOpts.ErrorHandler != nil {
 					eh = h.subOpts.ErrorHandler
 				}
-				offsets[msg.Topic][msg.Partition] = msg.Offset
+				offsets[msg.Topic][msg.Partition] = msg.Offset + 1
 				p := &publication{topic: msg.Topic, generation: h.generation, m: &m, offsets: offsets}
 
 				if err := h.brokerOpts.Codec.Unmarshal(msg.Value, &m); err != nil {