use 4.2.3-SNAPSHOT for hazelcast pom on 4.2 branch

src/plugins/hazelcast/pom.xml

@@ -4,7 +4,7 @@
     <parent>
         <artifactId>plugins</artifactId>
         <groupId>org.igniterealtime.openfire</groupId>
-        <version>4.2.0</version>
+        <version>4.2.3-SNAPSHOT</version>
     </parent>
     <groupId>org.igniterealtime.openfire.plugins</groupId>
     <artifactId>hazelcast</artifactId>