build(deps): bump futures-channel from 0.3.13 to 0.3.21

Bumps [futures-channel](https://github.com/rust-lang/futures-rs) from 0.3.13 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](rust-lang/futures-rs@0.3.13...0.3.21)

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

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

Author: dependabot[bot]

Cargo.lock

@@ -18,7 +18,7 @@ crossbeam-channel = "0.5.0"
 dotenv = "0.15.0"
 fluidex-common = { git = "https://github.com/fluidex/common-rs", branch = "master", features = [ "kafka", "non-blocking-tracing", "rust-decimal-dingir-exchange" ] }
 futures = "0.3.13"
-futures-channel = "0.3.13"
+futures-channel = "0.3.21"
 futures-core = { version = "0.3.13", default-features = false }
 futures-util = { version = "0.3.13", default-features = false }
 hex = "0.4.3"