Fixes master build by updating kafka to the latest snapshot

Change-Id: I0aad7f5abb119e178656919741a3df1847201526
diff --git a/Makefile.vars.master b/Makefile.vars.master
index 455f5b4..d160578 100644
--- a/Makefile.vars.master
+++ b/Makefile.vars.master
@@ -31,5 +31,5 @@
 export TRELLIS_T3_VERSION      ?= 4.0.0-SNAPSHOT
 export FABRIC_TOFINO_VERSION   ?= master
 export UP4_VERSION             ?= master
-export KAFKA_ONOS_VERSION      ?= 2.5.0-SNAPSHOT
+export KAFKA_ONOS_VERSION      ?= 2.6.0-SNAPSHOT
 export FABRIC_TNA_VERSION      ?= master