Update .gitlab-ci.yml

2 jobs for master in 32 seconds (queued for 1 second)
Status Name Job ID Coverage
failed compile_pdf #318


canceled pages #317


Name Stage Failure
compile_pdf Test
      Refer to 'FabAcademy2018.log' for details
Latexmk: Use the -f option to force complete processing,
unless error was exceeding maximum runs, or warnings treated as errors.
=== TeX engine is 'pdfTeX'
Latexmk: Errors, so I did not complete making targets
make[1]: *** [Makefile:33: FabAcademy2018.pdf] Error 12
make[1]: Leaving directory '/builds/open-data/dkan-user-guide/_build/latex'
make: *** [Makefile:141: latexpdf] Error 2
ERROR: Job failed: exit code 1