include 7.2.1 as a version (elastic#43584)

Author: jakelandis

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

@@ -103,6 +103,7 @@ public class Version implements Comparable<Version>, ToXContentFragment {
     public static final Version V_7_1_1 = new Version(7010199, org.apache.lucene.util.Version.LUCENE_8_0_0);
     public static final Version V_7_1_2 = new Version(7010299, org.apache.lucene.util.Version.LUCENE_8_0_0);
     public static final Version V_7_2_0 = new Version(7020099, org.apache.lucene.util.Version.LUCENE_8_0_0);
+    public static final Version V_7_2_1 = new Version(7020199, org.apache.lucene.util.Version.LUCENE_8_0_0);
     public static final Version V_7_3_0 = new Version(7030099, org.apache.lucene.util.Version.LUCENE_8_1_0);
     public static final Version CURRENT = V_7_3_0;