Upgrading ASF parent to 13

git-svn-id: https://svn.apache.org/repos/asf/cocoon/trunk@1439776 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/parent/pom.xml b/parent/pom.xml
index 9497c4e..f6f3011 100644
--- a/parent/pom.xml
+++ b/parent/pom.xml
@@ -24,8 +24,8 @@
   <parent>
     <groupId>org.apache</groupId>
     <artifactId>apache</artifactId>
-    <version>12</version>
-    <relativePath />
+    <version>13</version>
+    <relativePath/>
   </parent>
 
   <groupId>org.apache.cocoon</groupId>