Added bwc version 2.3.1

Author: opensearch-ci-bot

.ci/bwcVersions

@@ -51,4 +51,5 @@ BWC_VERSION:
   - "2.2.1"
   - "2.2.2"
   - "2.3.0"
+  - "2.3.1"
   - "2.4.0"

server/src/main/java/org/opensearch/Version.java

@@ -98,6 +98,7 @@ public class Version implements Comparable<Version>, ToXContentFragment {
     public static final Version V_2_2_1 = new Version(2020199, org.apache.lucene.util.Version.LUCENE_9_3_0);
     public static final Version V_2_2_2 = new Version(2020299, org.apache.lucene.util.Version.LUCENE_9_3_0);
     public static final Version V_2_3_0 = new Version(2030099, org.apache.lucene.util.Version.LUCENE_9_3_0);
+    public static final Version V_2_3_1 = new Version(2030199, org.apache.lucene.util.Version.LUCENE_9_3_0);
     public static final Version V_2_4_0 = new Version(2040099, org.apache.lucene.util.Version.LUCENE_9_3_0);
     public static final Version V_3_0_0 = new Version(3000099, org.apache.lucene.util.Version.LUCENE_9_4_0);
     public static final Version CURRENT = V_3_0_0;