add required docker vars

.gitlab-ci.yml

-# In case something goes horribly wrong, you can fall back to `image: ruby:2.5`
-image: $CI_REGISTRY/r3/docker/jekyll-lcsb:1.6
-
 stages:
   - prepare
   - save
@@ -9,6 +6,11 @@ stages:
   - deploy
   - trigger
 
+variables:
+    GIT_STRATEGY: clone
+    DOCKER_DRIVER: overlay2
+    DOCKER_TLS_CERTDIR: ""
+
 # prepare
 # ------------------------------------------------------------------------------------
 
@@ -66,6 +68,7 @@ save:commitIndex:
 # ------------------------------------------------------------------------------------
 
 build:pages:
+  image: $CI_REGISTRY/r3/docker/jekyll-lcsb:1.8
   stage: build
   variables:
     JEKYLL_ENV: production