chore(deps): bump tokio from 1.20.1 to 1.21.0 (#14274)

* chore(deps): bump tokio from 1.20.1 to 1.21.0

Bumps [tokio](https://github.com/tokio-rs/tokio) from 1.20.1 to 1.21.0.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](https://github.com/tokio-rs/tokio/compare/tokio-1.20.1...tokio-1.21.0)

---
updated-dependencies:
- dependency-name: tokio
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

* Fix unused lock guard in test

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Bruce Guenter <bruce.guenter@datadoghq.com>