Merge branch 'update-gitlab-shell-8-3-3' into 'master'

Update GitLab Shell to v8.3.3

See merge request gitlab-org/gitlab-ce!21750

GITLAB_SHELL_VERSION

-8.3.2
+8.3.3

changelogs/unreleased/update-gitlab-shell-8-3-3.yml

+---
+title: Update GitLab Shell to v8.3.3
+merge_request: 21750
+author:
+type: fixed