Bump redis from 4.6.11 to 4.6.12 in /server

Bumps [redis](https://github.com/redis/node-redis) from 4.6.11 to 4.6.12.
- [Release notes](https://github.com/redis/node-redis/releases)
- [Changelog](https://github.com/redis/node-redis/blob/master/CHANGELOG.md)
- [Commits](https://github.com/redis/node-redis/compare/[email protected]@4.6.12)

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

Signed-off-by: dependabot[bot] <[email protected]>