Update hdpath requirement from 0.2.0 to 0.4.0 in /relayer (#353)

Updates the requirements on [hdpath](https://github.com/emeraldpay/hdpath-rs) to permit the latest version.
- [Release notes](https://github.com/emeraldpay/hdpath-rs/releases)
- [Commits](https://github.com/emeraldpay/hdpath-rs/commits)

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

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

relayer/Cargo.toml

@@ -33,7 +33,7 @@ k256 = { version = "0.5.6", features = ["ecdsa-core", "ecdsa", "sha256"]}
 hex = "0.4"
 bitcoin = { version= "0.25"}
 bitcoin-wallet = "1.1.0"
-hdpath = { version = "0.2.0", features = ["with-bitcoin"] }
+hdpath = { version = "0.4.0", features = ["with-bitcoin"] }
 rust-crypto = "0.2.36"
 bech32 = "0.7.2"