Bump signal-hook from 0.3.17 to 0.3.18 (paritytech#3158)

Bumps [signal-hook](https://github.com/vorner/signal-hook) from 0.3.17 to 0.3.18.
- [Changelog](https://github.com/vorner/signal-hook/blob/master/CHANGELOG.md)
- [Commits](vorner/signal-hook@v0.3.17...v0.3.18)

---
updated-dependencies:
- dependency-name: signal-hook
  dependency-version: 0.3.18
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Cargo.lock

@@ -112,7 +112,7 @@ num-format = "0.4"
 num-traits = "0.2"
 rbtag = "0.3"
 structopt = "0.3"
-signal-hook = "0.3.15"
+signal-hook = "0.3.18"
 signal-hook-async-std = "0.2.2"
 strum = { version = "0.27.1", features = ["derive"] }
 pallet-bridge-parachains = { git = "https://github.com/paritytech/polkadot-sdk", branch = "master" }