Update .gitlab-ci.yml

1 job for simon.wimmer-master-patch-16198 in 5 seconds (queued for 2 seconds)
Name Stage Failure
build Build
Host key verification failed.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
fatal: clone of 'ssh://git@gitlab.ce.jku.at:10022/simon.wimmer/pandoc_pdf_tool.git' into submodule path '/builds/peter.eder/pandoc/pandoc_pdf_tool' failed
Failed to clone 'pandoc_pdf_tool' a second time, aborting
Cleaning up file based variables
ERROR: Job failed: exit code 1