Update .gitlab-ci.yml - switch AGU to master

1 job for master in 1 minute and 55 seconds
Status Job ID Name Coverage
failed build-start #9338612


Name Stage Failure
build-start Start
Triggering pipeline for ref 'dev' for project id 46440
Pipeline created (id: 1812812)
See pipeline at https://gitlab.cern.ch/nhardi/jalien-ci/pipelines/1812812
Waiting for pipeline 1812812 to finish ...
Pipeline failed! Check details at 'https://gitlab.cern.ch/nhardi/jalien-ci/pipelines/1812812'
Running after_script
Uploading artifacts for failed job
ERROR: Job failed: exit code 1