Make dsearles the sole maintainer

What does this MR do?

Set @dsearles as the sole maintainer

Evidence of maintainership:

• TOPIC ⡄ [sobelow] Move downstream QA expectations into the project: !33 (merged) gitlab-com/www-gitlab-com#11842 (comment 702161057)
• TOPIC ⡀ [sobelow] Add SEC_REGISTRY_IMAGE: !63 (merged) gitlab-com/www-gitlab-com#11842 (comment 702161610)
• TOPIC ⡄ [sobelow] Restrict openshift permissions: !54 (merged) gitlab-com/www-gitlab-com#11842 (comment 702161926)
• TOPIC ⡆ [sobelow] Create and set permissions for the .sobelow dir: !53 (merged) gitlab-com/www-gitlab-com#11842 (comment 702162586)
• TOPIC ⡄ [sobelow] Upgrade sobelow to v0.11.1: !50 (merged) gitlab-com/www-gitlab-com#11842 (comment 702164840)

What are the relevant issue numbers?

gitlab-com/www-gitlab-com#11842 (closed)

Does this MR meet the acceptance criteria?

• [-] Changelog entry added
• [-] Documentation created/updated for GitLab EE https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/10527
• [-] Documentation created/updated for this project, if necessary
• [-] Documentation reviewed by technical writer or follow-up review issue created
• [-] Tests added for this feature/bug
• [-] Job definition updated, if necessary
  • [-] Auto-DevOps template
  • [-] Job definition example
  • [-] CI Templates
• [-] Conforms to the code review guidelines
• [-] Conforms to the Go guidelines
• [-] Security reports checked/validated by reviewer