Bump futures from 0.3.30 to 0.3.31

Bumps [futures](https://github.com/rust-lang/futures-rs) from 0.3.30 to 0.3.31.
- [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@0.3.30...0.3.31)

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

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

Cargo.toml

@@ -13,7 +13,7 @@ rust-version = "1.61"
 [dependencies]
 delay_map = "0.4.0"
 discv5 = "0.6.0"
-futures = "0.3.30"
+futures = "0.3.31"
 hex = "0.4.3"
 home = "0.5.9"
 libp2p = { version = "0.53.2", default-features = false, features = ["dns", "tokio", "ecdsa", "noise", "macros", "secp256k1", "tcp", "yamux"] }