build(deps): bump syn from 2.0.67 to 2.0.68 (#3034)

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

---
updated-dependencies:
- dependency-name: syn
  dependency-type: indirect
  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>

Cargo.lock

@@ -3153,9 +3153,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.67"
+version = "2.0.68"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ff8655ed1d86f3af4ee3fd3263786bc14245ad17c4c7e85ba7187fb3ae028c90"
+checksum = "901fa70d88b9d6c98022e23b4136f9f3e54e4662c3bc1bd1d84a42a9a0f0c1e9"
 dependencies = [
  "proc-macro2",
  "quote",