FIX: correct debian version m)

.gitlab-ci.yml

+default:
+    image: debian-buster:latest
 before_script:
     ## dependencies
     
     - apt-get update -y
     - test -e  /etc/apt/sources.list.d/nodesource.list || curl -s https://deb.nodesource.com/gpgkey/nodesource.gpg.key | apt-key add -
-    - test -e  /etc/apt/sources.list.d/nodesource.list || echo 'deb https://deb.nodesource.com/node_13.x stretch main' > /etc/apt/sources.list.d/nodesource.list
+    - test -e  /etc/apt/sources.list.d/nodesource.list || echo 'deb https://deb.nodesource.com/node_13.x buster main' > /etc/apt/sources.list.d/nodesource.list
     - 'which npm || (apt-get update -y && apt-get install -y nodejs)'
     - apt-get install python3-requests
     - cd frontend/