pandoc --version yields:
pandoc --version
pandoc 1.12.2.1 Compiled with texmath 0.6.5.2, highlighting-kate 0.5.5.1. Syntax highlighting is supported for the followin
Try to add --listings option to your pandoc compile command:
--listings
pandoc --read=markdown --table-of-contents --toc-depth=2 --preserve-tabs --standalone --template=template.latex --latex-engine=xelatex --listings Hausarbeit.md --highlight-style=pygments -o Hausarbeit.pdf