chore: bump futures from 0.3.19 to 0.3.21 (#23476)

* chore: bump futures from 0.3.19 to 0.3.21

Bumps [futures](https://github.com/rust-lang/futures-rs) from 0.3.19 to 0.3.21.
- [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/0.3.19...0.3.21)

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

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

* [auto-commit] Update all Cargo lock files

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: dependabot-buildkite <dependabot-buildkite@noreply.solana.com>

ledger/Cargo.toml

@@ -16,7 +16,7 @@ chrono = { version = "0.4.11", features = ["serde"] }
 chrono-humanize = "0.2.1"
 crossbeam-channel = "0.5"
 fs_extra = "1.2.0"
-futures = "0.3.19"
+futures = "0.3.21"
 itertools = "0.10.3"
 lazy_static = "1.4.0"
 libc = "0.2.117"