Remove -SNAPSHOT version from 1.6.15

Author: sgarg-CS

pom.xml

@@ -22,7 +22,7 @@
   <name>Salesforce plugins</name>
   <groupId>io.cdap.plugin</groupId>
   <artifactId>salesforce-plugins</artifactId>
-  <version>1.6.15-SNAPSHOT</version>
+  <version>1.6.15</version>
   <packaging>jar</packaging>
   <description>Salesforce Plugins</description>
   <url>https://github.com/data-integrations/salesforce</url>