fix build error: switch sling API to 2.11 because 2.10 was never released

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1761884 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index a5ddac2..4490baf 100644
--- a/pom.xml
+++ b/pom.xml
@@ -183,7 +183,7 @@
 		<dependency>
 			<groupId>org.apache.sling</groupId>
 			<artifactId>org.apache.sling.api</artifactId>
-			<version>2.10.0</version>
+			<version>2.11.0</version>
             <scope>provided</scope>
 		</dependency>
         <dependency>