fix: Kafka source reads duplicated messages

[jy4096]

fix: #1408

https://github.com/IBM/sarama/blob/4b9e8f6681955d56471eafa1b43b62085a58e1c6/consumer_group.go#L687-L689

// To follow upstream conventions, you are expected to mark the offset of the
// next message to read, not the last message read. Thus, when calling `MarkOffset`
// you should typically add one to the offset of the last consumed message.

https://github.com/IBM/sarama/blob/4b9e8f6681955d56471eafa1b43b62085a58e1c6/consumer_group.go#L823-L825

func (s *consumerGroupSession) MarkMessage(msg *ConsumerMessage, metadata string) {
	s.MarkOffset(msg.Topic, msg.Partition, msg.Offset+1, metadata)
}

[whynowy]

A bug introduced by #949 :)

[yhl25]

Thank you for the fix @jy4096!