build(deps): bump tower-test from `35188ec` to `251296d`

Bumps [tower-test](https://github.com/tower-rs/tower) from `35188ec` to `251296d`.
- [Release notes](https://github.com/tower-rs/tower/releases)
- [Commits](https://github.com/tower-rs/tower/compare/35188ece3a5e05762c2eb64c675ef8c2d42e229a...251296dc54a044383dffd16d2179b443e2615672)

---
updated-dependencies:
- dependency-name: tower-test
  dependency-version: 251296dc54a044383dffd16d2179b443e2615672
  dependency-type: direct:production
...

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