Bump tokio from 1.8.3 to 1.8.4

Bumps [tokio](https://github.com/tokio-rs/tokio) from 1.8.3 to 1.8.4.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](tokio-rs/tokio@tokio-1.8.3...tokio-1.8.4)

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

Signed-off-by: Patrick J.P. Culp <jpculp@amazon.com>