Upgrade to JDK 14.

Change-Id: I58f3ae6c7a048daf34ea79274a6b6154bb8679f4
diff --git a/src/main/docker/Dockerfile.jvm b/src/main/docker/Dockerfile.jvm
index e059b5d..3cfb947 100644
--- a/src/main/docker/Dockerfile.jvm
+++ b/src/main/docker/Dockerfile.jvm
@@ -14,7 +14,7 @@
 # docker run -i --rm -p 8080:8080 docker.benkard.de/mulk/mulkcms2
 #
 ###
-FROM adoptopenjdk:13-jre-hotspot
+FROM adoptopenjdk:14-jre-hotspot
 
 RUN mkdir -p /deployments