Bump mail_room to 0.0.6
See:
- Original issue: gitlab-org/gitlab#222787 (closed)
- Upstream fix: https://github.com/tpitale/mail_room/pull/112 (upstream fix)
- Mirror MR: https://gitlab.com/gitlab-org/gitlab-mail_room/-/merge_requests/12
- 0.0.6 Release: https://gitlab.com/gitlab-org/gitlab-mail_room/-/issues/13
Edited by charlie ablett