Fix intermittent test failures in AppVeyor
Fix intermittent test failures in AppVeyor

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