Bump futures from 0.3.27 to 0.3.28 (#2420)

Bumps [futures](https://github.com/rust-lang/futures-rs) from 0.3.27 to 0.3.28.
- [Release notes](https://github.com/rust-lang/futures-rs/releases)
- [Changelog](https://github.com/rust-lang/futures-rs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-lang/futures-rs/compare/0.3.27...0.3.28)

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

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

cumulus/test/service/Cargo.toml

@@ -72,7 +72,7 @@ cumulus-relay-chain-minimal-node = { path = "../../client/relay-chain-minimal-no
 cumulus-client-pov-recovery = { path = "../../client/pov-recovery" }
 
 [dev-dependencies]
-futures = "0.3.27"
+futures = "0.3.28"
 portpicker = "0.1.1"
 
 # Polkadot dependencies