YAKHMI-738 set packaging type to tycho supporting eclipse-repository

releng/org.yakindu.sct.releng/category.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<site>
+   <category-def name="dummy" label="empty category to support eclipse-repository packaging"/>
+</site>

releng/org.yakindu.sct.releng/promote-pom.xml

@@ -10,7 +10,7 @@
 		<relativePath>../org.yakindu.sct.releng/pom.xml</relativePath>
 	</parent>
 	<artifactId>org.yakindu.sct.releng.promote</artifactId>
-	<packaging>pom</packaging>
+	<packaging>eclipse-repository</packaging>
 
 	<!-- Search for 'target architecture' to find places where the architecture for distros is set -->