Update .gitlab-ci.yml

1 job for master in 6 seconds
Name Stage Failure
failed
build Test
Running with gitlab-runner 12.5.0 (577f813d)
on docekr 2 LxzwyCca
Using Docker executor with image 3.6.3-jdk-8 ...
Pulling docker image 3.6.3-jdk-8 ...
ERROR: Job failed: Error response from daemon: pull access denied for 3.6.3-jdk-8, repository does not exist or may require 'docker login': denied: requested access to the resource is denied (executor_docker.go:188:1s)