Update thiserror requirement from 1.0 to 2.0

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...2.0.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Cargo.toml

@@ -20,7 +20,7 @@ features = ["nightly"]
 reddsa = "0.5.0"
 rand_core = "0.6"
 serde = { version = "1", optional = true, features = ["derive"] }
-thiserror = "1.0"
+thiserror = "2.0"
 zeroize = { version = "1", default-features = false, features = ["zeroize_derive"] }
 
 [dev-dependencies]