GitLab CI: forgot the `-y` on apt-get

1 job for master in 2 minutes (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #584
build

00:02:00

 
Name Stage Failure
failed
build Test There is an unknown failure, please try again
  method               = "GET"
proxy = Nothing
rawBody = False
redirectCount = 10
responseTimeout = ResponseTimeoutDefault
requestVersion = HTTP/1.1
}
(ConnectionFailure Network.BSD.getProtocolByName: does not exist (no such protocol name: tcp))
ERROR: Job failed: exit code 1