Merge branch 'bump-pages' into 'master'

Bump GitLab Pages to 0.2.4

This fixes 404 Content-Type that were supposed to be fixed last time.

cc @axil @dblessing 


See merge request !394

CHANGELOG

@@ -64,6 +64,7 @@ v 8.7.4
   - Running rake gitlab:db:drop_tables now drops tables with cascade !4020
   - Running rake gitlab:db:drop_tables uses "IF EXISTS" as a precaution !4100
   - Use a case-insensitive comparison in sanitizing URI schemes
+  - Bump GitLab Pages to 0.2.4 to fix Content-Type for predefined 404
 
 v 8.7.3
   - Emails, Gitlab::Email::Message, Gitlab::Diff, and Premailer::Adapter::Nokogiri are now instrumented

GITLAB_PAGES_VERSION

-0.2.2
+0.2.4