Update thiserror requirement from 1.0 to 2.0 (#491)

Updates the requirements on [thiserror](https://github.com/dtolnay/thiserror) to permit the latest version.
- [Release notes](https://github.com/dtolnay/thiserror/releases)
- [Commits](dtolnay/thiserror@1.0.0...2.0.3)

---
updated-dependencies:
- dependency-name: thiserror
  dependency-type: direct:production
...

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

tarpc/Cargo.toml

@@ -50,7 +50,7 @@ rand = "0.8"
 serde = { optional = true, version = "1.0", features = ["derive"] }
 static_assertions = "1.1.0"
 tarpc-plugins = { path = "../plugins", version = "0.14" }
-thiserror = "1.0"
+thiserror = "2.0"
 tokio = { version = "1", features = ["time"] }
 tokio-util = { version = "0.7.3", features = ["time"] }
 tokio-serde = { optional = true, version = "0.9" }