Pin Ruby in CI to version 2.*

.gitlab-ci.yml

@@ -108,7 +108,7 @@ stages:
 build:latest:
   <<: *builds
   <<: *latest_before_script
-  image: ruby:latest
+  image: ruby:2
   allow_failure: true
 
 # Job runs jekyll build latest dependencies,
@@ -116,7 +116,7 @@ build:latest:
 build:production:subpath:
   <<: *builds
   <<: *production_before_script
-  image: ruby:latest
+  image: ruby:2
   variables:
     <<: *common_variables
     SUBPATH: /$CI_PROJECT_NAME