Update .gitlab-ci.yml

1 job for master in 1 second (queued for 3 seconds)
Name Stage Failure
failed
build Test
 * [new ref]         refs/pipelines/241 -> refs/pipelines/241
9347208..c60176b master -> origin/master
Checking out c60176b5 as master...
Removing target/
Skipping Git submodules setup
$ export JAVA_HOME=/usr/bin/java; mvn package -B
Error: JAVA_HOME is not defined correctly.
We cannot execute /usr/bin/java/bin/java
ERROR: Job failed: exit status 1