Update .gitlab-ci.yml

1 job for gitlab-ci in 1 minute and 34 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
failed #45
alpine docker
build

00:01:34

 
Name Stage Failure
failed
build Build There is an unknown failure, please try again
 CURL admin/killsource?mount=%2Ffoo.ogg
OK [200 OK]

All tests done

Terminated SOURCE1
Terminated SOURCE2
Terminated Icecast
ERROR: Job failed: exit code 1