Update .gitlab-ci.yml

.gitlab-ci.yml

@@ -2,7 +2,8 @@ image: debian:stretch
 
 build:
   script:
-  - apt install pandoc python3-pip
+  - echo "deb http://deb.debian.org/debian stretch main" > /etc/apt/sources.list
+  - apt-get install pandoc python3-pip
   - pip3 install MarkdownPP
   - mkdir public
   - markdown-pp index.mdpp -o public/Satzung.mkd