Update .gitlab-ci.yml

1 job for master in 18 seconds
Name Stage Failure
failed
scripts Build
   88a5457..30a10b8  master     -> origin/master
Checking out 30a10b8a as master...
Updating/initializing submodules recursively...
Authenticating with credentials from job payload (GitLab Registry)
$ eval $(ssh-agent -s)
Agent pid 12
$ ssh-add <(echo "$SSH_PRIVATE_KEY")
Error loading key "/dev/fd/63": invalid format
ERROR: Job failed: exit code 1