Bump minimum required Koral version from 0.38.1 to 0.39

This makes sure that a Java 11 compiled version of Koral is used.

Change-Id: I63e46d1317ab1668e66425bee8f3f2c2edf24222
diff --git a/core/pom.xml b/core/pom.xml
index fad8f38..9059e4d 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -15,7 +15,7 @@
 		<flyway.version>9.8.1</flyway.version>
 		<log4j.version>2.19.0</log4j.version>
 		<krill.version>[0.60.4,)</krill.version>
-		<koral.version>[0.38.1,)</koral.version>
+		<koral.version>[0.39,)</koral.version>
 	</properties>
 	
 	<build>