adjust CI to new inputs

.gitlab-ci.yml

@@ -4,6 +4,9 @@ before_script:
   - python --version
   - python -m pip install --upgrade pip
   - pip install -r requirements.txt
+  - export IMAGE_TAG=$CI_IMAGE_TAG
+  - export IMAGE_DOCKERHUB_USER=&DOCKERHUB_USER
+  - export IMAGE_DOCKERHUB_PASSWORD=$DOCKERHUB_PASSWORD
 
 stages:
   - lint&test