chore(deps): bump fedimint-rocksdb from v0.1.5 to v0.2.1

Bumps [fedimint-rocksdb](https://github.com/fedimint/fedimint) from v0.1.5 to v0.2.1.
- [Release notes](https://github.com/fedimint/fedimint/releases)
- [Commits](fedimint/fedimint@94edc84...a8422b8)

---
updated-dependencies:
- dependency-name: fedimint-rocksdb
  dependency-type: direct:production
...

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