Cache .m2 dependencies

Previously, every docker build downloaded Maven dependencies on every build.
This enables reuse .m2 folder across builds which significantly improves the build times.

Signed-off-by: Vladimir Sitnikov <[email protected]>

Author: vlsi

Dockerfile

@@ -26,7 +26,7 @@ COPY .mvn $APP_HOME/.mvn
 COPY mvnw $APP_HOME
 
 WORKDIR $APP_HOME
-RUN ./mvnw package -Dlicense.skip=true -DskipTests && rm -rf ~/.m2
+RUN --mount=type=cache,target=/root/.m2 ./mvnw package -Dlicense.skip=true -DskipTests
 
 FROM eclipse-temurin:11-jre
 MAINTAINER Pavol Loffay <[email protected]>