Add 2.18.0 version (opensearch-project#15712)

Signed-off-by: Andriy Redko <andriy.redko@aiven.io>

Author: reta

.ci/bwcVersions

@@ -38,3 +38,4 @@ BWC_VERSION:
   - "2.16.0"
   - "2.16.1"
   - "2.17.0"
+  - "2.18.0"

libs/core/src/main/java/org/opensearch/Version.java

@@ -109,6 +109,7 @@ public class Version implements Comparable<Version>, ToXContentFragment {
     public static final Version V_2_16_0 = new Version(2160099, org.apache.lucene.util.Version.LUCENE_9_11_1);
     public static final Version V_2_16_1 = new Version(2160199, org.apache.lucene.util.Version.LUCENE_9_11_1);
     public static final Version V_2_17_0 = new Version(2170099, org.apache.lucene.util.Version.LUCENE_9_11_1);
+    public static final Version V_2_18_0 = new Version(2180099, org.apache.lucene.util.Version.LUCENE_9_11_1);
     public static final Version V_3_0_0 = new Version(3000099, org.apache.lucene.util.Version.LUCENE_9_12_0);
     public static final Version CURRENT = V_3_0_0;