chore(deps): bump futures-executor from 0.3.15 to 0.3.16 (#351)

Bumps [futures-executor](https://github.com/rust-lang/futures-rs) from 0.3.15 to 0.3.16.
- [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@0.3.15...0.3.16)

---
updated-dependencies:
- dependency-name: futures-executor
  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>

ethers-signers/Cargo.toml

@@ -27,7 +27,7 @@ sha2 = { version = "0.9.3", default-features = false }
 rand = { version = "0.8.4", default-features = false }
 yubihsm = { version = "0.39.0", features = ["secp256k1", "http", "usb"], optional = true }
 futures-util = "0.3.16"
-futures-executor = "0.3.14"
+futures-executor = "0.3.16"
 
 [dev-dependencies]
 ethers = { version = "0.4.0", path = "../ethers" }