Merge branch 'security-pages-toctou-race' into 'master'

[master] [pages] Possible symlink time of check to time of use race condition

Closes #2742

See merge request gitlab/gitlabhq!2638

GITLAB_PAGES_VERSION

-1.3.0
+1.3.1

changelogs/unreleased/security-pages-toctou-race.yml

+---
+title: Fix a possible symlink time of check to time of use race condition in GitLab
+  Pages
+merge_request:
+author:
+type: security