Trying this

.gitlab-ci.yml

@@ -3,6 +3,7 @@ image: ruby:2.5
 pages:
   script:
   - gem install jekyll
+  - gem install jekyll-paginate
   - jekyll build -d public/
   artifacts:
     paths:

Gemfile

 source 'https://rubygems.org/'
 
 gem 'jekyll'
+
+group :jekyll_plugins do
+	gem 'jekyll-paginate'
+end
\ No newline at end of file