Update snapshot version to 15.0.0 (#852)

Author: sharanrudresh

pom.xml

@@ -9,7 +9,7 @@
     </parent>
 
     <artifactId>kafka-connect-elasticsearch</artifactId>
-    <version>14.3.0-SNAPSHOT</version>
+    <version>15.0.0-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>kafka-connect-elasticsearch</name>
     <organization>