Change base image to openjdk with early access version

Author: cjneasbi

Dockerfile

@@ -1,5 +1,5 @@
 ARG JDK_VERSION
-FROM openjdk:${JDK_VERSION}-jre-slim
+FROM openjdk:${JDK_VERSION}-ea-slim
 
 ARG MVN_VERSION=1.2-SNAPSHOT
 ENV MVN_VERSION=${MVN_VERSION}