Update .gitlab-ci.yml

1 job for master in 19 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #99
pages
build

00:00:19

 
Name Stage Failure
failed
build Test There is an unknown failure, please try again
? 
! Emergency stop.
...

l.165 \end{frame}

! ==> Fatal error occurred, no output PDF file produced!
Transcript written on main.log.
ERROR: Job failed: exit code 1