build(deps): bump tower-test from `251296d` to `df06d70`

Bumps [tower-test](https://github.com/tower-rs/tower) from `251296d` to `df06d70`.
- [Release notes](https://github.com/tower-rs/tower/releases)
- [Commits](https://github.com/tower-rs/tower/compare/251296dc54a044383dffd16d2179b443e2615672...df06d70dbea345facbffb5881fe8647f53bf424d)

---
updated-dependencies:
- dependency-name: tower-test
  dependency-version: df06d70dbea345facbffb5881fe8647f53bf424d
  dependency-type: direct:production
...

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