[CI] Test against 6.8.6 of Elasticsearch

Author: picandocodigo

.ci/run-tests

@@ -11,8 +11,8 @@
 
 set -eo pipefail
 
-export RUBY_TEST_VERSION=${RUBY_TEST_VERSION:-2.6.1}
-export ELASTICSEARCH_VERSION=${ELASTICSEARCH_VERSION:-6.8.0}
+export RUBY_TEST_VERSION=${RUBY_TEST_VERSION:-2.6.5}
+export ELASTICSEARCH_VERSION=${ELASTICSEARCH_VERSION:-6.8.6}
 export SINGLE_TEST=${SINGLE_TEST}
 
 set +x
@@ -40,4 +40,4 @@ docker build \
   .
 
 
-sh .ci/docker/run-${TEST_SUITE}
+sh .ci/docker/run-${TEST_SUITE}