chore(deps): bump ra from 3.1.7 to 3.1.8

Bumps [ra](https://github.com/rabbitmq/ra) from 3.1.7 to 3.1.8.
- [Release notes](https://github.com/rabbitmq/ra/releases)
- [Commits](rabbitmq/ra@v3.1.7...v3.1.8)

---
updated-dependencies:
- dependency-name: ra
  dependency-version: 3.1.8
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]