Bump rails from 5.2.4.3 to 5.2.8.1

Bumps [rails](https://github.com/rails/rails) from 5.2.4.3 to 5.2.8.1.
- [Release notes](https://github.com/rails/rails/releases)
- [Commits](https://github.com/rails/rails/compare/v5.2.4.3...v5.2.8.1

)

---
updated-dependencies:
- dependency-name: rails
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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