Add and install python packages

.gitlab-ci.yml

@@ -2,6 +2,9 @@ image: stretch_website
 
 before_script:
   - export LANG=en_US.UTF-8
+  - python -m venv venv
+  - source venv/bin/activate
+  - pip install -r requirements.txt
 
 stages:
   - test

requirements.txt

+PyYAML==3.13