limit ci jobs to docker runners

.gitlab-ci.yml

@@ -9,6 +9,8 @@ build:
   image:
     name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]
+  tags:
+    - docker
   script:
     - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
     - /kaniko/executor --context $CI_PROJECT_DIR --dockerfile $CI_PROJECT_DIR/Dockerfile --destination $CI_REGISTRY_IMAGE:$CI_COMMIT_TAG
@@ -17,6 +19,9 @@ build:
 
 
 test:
+  tags:
+    - docker
+  image: python:3.7
   stage: test
   script:
     - python setup.py test