[skip ci] Add pagination classes

app/views/kaminari/gitlab/_without_count.html.haml

 .gl-pagination
   %ul.pagination.clearfix
     - if previous_path
-      %li.prev
-        = link_to(t('views.pagination.previous'), previous_path, rel: 'prev')
+      %li.page-item.prev
+        = link_to(t('views.pagination.previous'), previous_path, rel: 'prev', class: 'page-link')
     - if next_path
-      %li.next
-        = link_to(t('views.pagination.next'), next_path, rel: 'next')
+      %li.page-item.next
+        = link_to(t('views.pagination.next'), next_path, rel: 'next', class: 'page-link')