Add latex engine to command line to have effect

.gitlab-ci.yml

@@ -15,7 +15,7 @@ build_pandoc:
     script:
         - pwd
         - sudo docker run --rm -v $(pwd):/source docker.rz.tu-harburg.de:5000/docker/pandoc4gitbook
-        - mkdir -p book_pdf; sudo docker run --rm -v $(pwd):/source docker.rz.tu-harburg.de:5000/docker/pandoc .pandoc-config.yml book.md -o book_pdf/pandocbook.pdf --template=gitbook.latex
+        - mkdir -p book_pdf; sudo docker run --rm -v $(pwd):/source docker.rz.tu-harburg.de:5000/docker/pandoc .pandoc-config.yml book.md -o book_pdf/pandocbook.pdf --template=gitbook.latex --latex-engine=xelatex
         - sudo chown -R gitlab-runner:gitlab-runner $HOME
 
     artifacts: