MAINT: build docker env only nightly

.gitlab-ci.yml

@@ -87,6 +87,9 @@ build-testenv:
   image: docker:19.03
   stage: setup
   timeout: 3 h
+  only:
+    - web
+    - shedules
   script: 
     - cd test/docker
     - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY