Update to parent pom 48 (#16)

diff --git a/pom.xml b/pom.xml
index 989b3ca..56ab80e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>org.apache.sling</groupId>
     <artifactId>sling</artifactId>
-    <version>29</version>
+    <version>48</version>
     <relativePath />
   </parent>