Add Node 18 and 20

Remove Node 12-16 but we keep the images on the registry

.gitlab-ci.yml

@@ -10,7 +10,7 @@ node:
   stage: build
   parallel:
     matrix:
-      - VERSION: ['12-stretch-slim','13-stretch-slim','14-stretch-slim','16-stretch-slim','18-stretch-slim']
+      - VERSION: ['18-slim','20-slim']
   script:
     - docker build --pull --build-arg NODE_VERSION=${VERSION} -t $CI_REGISTRY_IMAGE:${VERSION} .
     - docker push $CI_REGISTRY_IMAGE:${VERSION}