Bump rubocop-thread_safety from 0.4.4 to 0.5.1 (#12870)

* Bump rubocop-thread_safety from 0.4.4 to 0.5.1

Bumps [rubocop-thread_safety](https://github.com/rubocop/rubocop-thread_safety) from 0.4.4 to 0.5.1.
- [Commits](rubocop/rubocop-thread_safety@v0.4.4...v0.5.1)

---
updated-dependencies:
- dependency-name: rubocop-thread_safety
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

* update .rubocop_todo.yml

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Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Ryan McNeil <ryan.mcneil@oddball.io>