chore(deps): update rig-core requirement from 0.10.0 to 0.12.0 (#231)

Updates the requirements on [rig-core](https://github.com/0xPlaygrounds/rig) to permit the latest version.
- [Release notes](https://github.com/0xPlaygrounds/rig/releases)
- [Commits](https://github.com/0xPlaygrounds/rig/compare/rig-core-v0.10.0...rig-core-v0.12.0)

---
updated-dependencies:
- dependency-name: rig-core
  dependency-version: 0.12.0
  dependency-type: direct:production
...

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

examples/rig-integration/Cargo.toml

@@ -12,7 +12,7 @@ categories = { workspace = true }
 readme = { workspace = true }
 
 [dependencies]
-rig-core = "0.10.0"
+rig-core = "0.12.0"
 tokio = { version = "1", features = ["full"] }
 rmcp = { path = "../../crates/rmcp", features = [
     "client",