Bump versions after 8.4.2 release

.ci/bwcVersions

@@ -73,4 +73,5 @@ BWC_VERSION:
   - "8.4.0"
   - "8.4.1"
   - "8.4.2"
+  - "8.4.3"
   - "8.5.0"

.ci/snapshotBwcVersions

@@ -1,4 +1,4 @@
 BWC_VERSION:
   - "7.17.7"
-  - "8.4.2"
+  - "8.4.3"
   - "8.5.0"

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

@@ -121,6 +121,7 @@ public class Version implements Comparable<Version>, ToXContentFragment {
     public static final Version V_8_4_0 = new Version(8_04_00_99, org.apache.lucene.util.Version.LUCENE_9_3_0);
     public static final Version V_8_4_1 = new Version(8_04_01_99, org.apache.lucene.util.Version.LUCENE_9_3_0);
     public static final Version V_8_4_2 = new Version(8_04_02_99, org.apache.lucene.util.Version.LUCENE_9_3_0);
+    public static final Version V_8_4_3 = new Version(8_04_03_99, org.apache.lucene.util.Version.LUCENE_9_3_0);
     public static final Version V_8_5_0 = new Version(8_05_00_99, org.apache.lucene.util.Version.LUCENE_9_4_0);
     public static final Version CURRENT = V_8_5_0;