Update .gitlab-ci.yml

1 job from master in 1 second (queued for 1 second)
Status Job ID Name Coverage
  Build
failed #9483
build

00:00:01

 
Name Stage Failure
failed
build Build
./.git/objects/e8
./.git/objects/bf
./.git/refs
./.git/refs/tags
./.git/refs/heads
./.git/refs/remotes
./.git/refs/remotes/origin
bash: line 73: javac: command not found
ERROR: Job failed: exit status 1