Bump syn from 2.0.67 to 2.0.68 in /src/wasm-lib (#2761)

Bumps [syn](https://github.com/dtolnay/syn) from 2.0.67 to 2.0.68.
- [Release notes](https://github.com/dtolnay/syn/releases)
- [Commits](https://github.com/dtolnay/syn/compare/2.0.67...2.0.68)

---
updated-dependencies:
- dependency-name: syn
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

src/wasm-lib/derive-docs/Cargo.toml

@@ -20,7 +20,7 @@ quote = "1"
 regex = "1.10"
 serde = { version = "1.0.203", features = ["derive"] }
 serde_tokenstream = "0.2"
-syn = { version = "2.0.67", features = ["full"] }
+syn = { version = "2.0.68", features = ["full"] }
 
 [dev-dependencies]
 anyhow = "1.0.86"