Update CI to 8.6 (#3010)

Author: mgravell

tests/RedisConfigs/.docker/Redis/Dockerfile

@@ -1,5 +1,4 @@
-FROM redislabs/client-libs-test:8.4-GA-pre.3
-
+FROM redislabs/client-libs-test:8.6.0
 COPY --from=configs ./Basic /data/Basic/
 COPY --from=configs ./Failover /data/Failover/
 COPY --from=configs ./Cluster /data/Cluster/