Updated koral version.

Change-Id: I5fb5b9bedd1bcc602494a727a03f3ecbbfdd34d5
diff --git a/core/pom.xml b/core/pom.xml
index 465f0b9..e82c424 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -213,7 +213,7 @@
 		<dependency>
 			<groupId>de.ids_mannheim.korap</groupId>
 			<artifactId>Koral</artifactId>
-			<version>0.27</version>
+			<version>0.28</version>
 			<exclusions>
 				<exclusion>
 					<groupId>org.eclipse.jetty</groupId>