Update thiserror requirement from 1.0.31 to 2.0.3

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@1.0.31...2.0.3)

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

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

positional/Cargo.toml

@@ -25,7 +25,7 @@ pad = "0.1.6"
 positional_derive = {version = "=0.4.3", path = "../positional_derive"}
 proc-macro2 = "1.0.39"
 quote = "1.0"
-thiserror = "1.0.31"
+thiserror = "2.0.3"
 
 [dev-dependencies]
 chrono = "0.4.19"