Update syn requirement from 1.0.107 to 2.0.37

Updates the requirements on [syn](https://github.com/dtolnay/syn) to permit the latest version.
- [Release notes](https://github.com/dtolnay/syn/releases)
- [Commits](dtolnay/syn@1.0.107...2.0.37)

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

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

rtic-macros/Cargo.toml

@@ -44,7 +44,7 @@ indexmap = "2.0.0"
 proc-macro2 = "1.0.49"
 proc-macro-error = "1.0.4"
 quote = "1.0.23"
-syn = { version = "1.0.107", features = ["extra-traits", "full"] }
+syn = { version = "2.0.37", features = ["extra-traits", "full"] }
 
 [dev-dependencies]
 trybuild = "1.0.73"