build(deps): bump gadget-sdk from 0.4.0 to 0.5.1

Bumps [gadget-sdk](https://github.com/tangle-network/gadget) from 0.4.0 to 0.5.1.
- [Release notes](https://github.com/tangle-network/gadget/releases)
- [Changelog](https://github.com/tangle-network/gadget/blob/main/release-plz.toml)
- [Commits](tangle-network/gadget@gadget-sdk-v0.4.0...gadget-sdk-v0.5.1)

---
updated-dependencies:
- dependency-name: gadget-sdk
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Cargo.toml

@@ -20,7 +20,7 @@ tokio = { version = "1.41", default-features = false, features = ["full"] }
 serde = { version = "1", features = ["derive"] }
 
 [dependencies.gadget-sdk]
-version = "0.4.0"
+version = "0.5.1"
 features = ["getrandom"]
 
 [dependencies.libp2p]