Bump merlin from 2.0.0 to 3.0.0

Bumps [merlin](https://github.com/zkcrypto/merlin) from 2.0.0 to 3.0.0.
- [Release notes](https://github.com/zkcrypto/merlin/releases)
- [Changelog](https://github.com/zkcrypto/merlin/blob/main/CHANGELOG.md)
- [Commits](zkcrypto/merlin@2.0.0...3.0.0)

---
updated-dependencies:
- dependency-name: merlin
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

node/core/approval-voting/Cargo.toml

@@ -11,7 +11,7 @@ parity-scale-codec = { version = "3.1.5", default-features = false, features = [
 gum = { package = "tracing-gum", path = "../../gum" }
 bitvec = { version = "1.0.0", default-features = false, features = ["alloc"] }
 lru = "0.8"
-merlin = "2.0"
+merlin = "3.0"
 schnorrkel = "0.9.1"
 kvdb = "0.12.0"
 derive_more = "0.99.17"