Fix handling of task within SendAsync
Fix handling of task within SendAsync

Thanks to vchekan for pointing this one out.

martijnhoekstra/kafka-net,bridgewell/kafka-net,gigya/KafkaNetClient,PKRoma/kafka-net,nightkid1027/kafka-net,geffzhang/kafka-net,Jroland/kafka-net,CenturyLinkCloud/kafka-net,EranOfer/KafkaNetClient,aNutForAJarOfTuna/kafka-net,BDeus/KafkaNetClient