Update to latest parent pom 20

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1622028 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 1b7be13..ed5d345 100644
--- a/pom.xml
+++ b/pom.xml
@@ -23,7 +23,7 @@
     <parent>
         <groupId>org.apache.sling</groupId>
         <artifactId>sling</artifactId>
-        <version>19</version>
+        <version>20</version>
         <relativePath>../../../parent/pom.xml</relativePath>
     </parent>