Don't use services in update job

.gitlab-ci.yml

@@ -3,7 +3,7 @@ image: docker:latest
 # When using dind, it's wise to use the overlayfs driver for
 # improved performance.
 variables:
-  DOCKER_DRIVER: overlay
+  DOCKER_DRIVER: overlay2
   IMAGE_NAME: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME
   IMAGE_LATEST: $CI_REGISTRY_IMAGE:latest
 
@@ -38,6 +38,7 @@ deploy:
 update:
   image: python:3.6
   before_script: []
+  services: []
   script:
     - pip install requests
     - ./update.py $API_TOKEN $CI_PROJECT_PATH