[pom] Update assembly goal to single

Author: hazendaz

pom.xml

@@ -122,7 +122,7 @@
                         <id>dist-src</id>
                         <phase>package</phase>
                         <goals>
-                            <goal>attached</goal>
+                            <goal>single</goal>
                         </goals>
                         <configuration>
                             <descriptors>