SLING-7253 Upgrade Karaf to 4.2

use Karaf 4.2.0.M2
diff --git a/pom.xml b/pom.xml
index 7eece47..af0e6bd 100644
--- a/pom.xml
+++ b/pom.xml
@@ -44,7 +44,7 @@
   <!-- https://github.com/apache/karaf/blob/master/assemblies/apache-karaf/pom.xml -->
 
   <properties>
-    <org.apache.karaf.version>4.2.0.M1</org.apache.karaf.version>
+    <org.apache.karaf.version>4.2.0.M2</org.apache.karaf.version>
   </properties>
 
   <dependencies>