Update syn requirement from 1.0 to 2.0

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@1.0.0...2.0.66)

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

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

Cargo.toml

@@ -84,7 +84,7 @@ url = "2.1.1"
 chrono = "0.4.31"
 trybuild = "1.0.65"
 proc-macro2 = "1.0"
-syn = "1.0"
+syn = "2.0"
 quote = "1.0.3"
 num-bigint = "0.4"
 ratchet = { package = "ratchet_rs", version = "0.4" }