Update opensearchproject/opensearch Docker tag to v2.18.0 (#1812)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

docker-compose.opensearch.base.yml

@@ -1,6 +1,6 @@
 services:
   opensearch:
-    image: opensearchproject/opensearch:2.17.1
+    image: opensearchproject/opensearch:2.18.0
     environment:
       - "cluster.name=opensearch-cluster"
       - "bootstrap.memory_lock=true" # along with the memlock settings below, disables swapping