cargo: bump syn from 1.0.83 to 1.0.84

Bumps [syn](https://github.com/dtolnay/syn) from 1.0.83 to 1.0.84.
- [Release notes](https://github.com/dtolnay/syn/releases)
- [Commits](https://github.com/dtolnay/syn/compare/1.0.83...1.0.84)

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

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

Cargo.lock

@@ -3623,9 +3623,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "1.0.83"
+version = "1.0.84"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "23a1dfb999630e338648c83e91c59a4e9fb7620f520c3194b6b89e276f2f1959"
+checksum = "ecb2e6da8ee5eb9a61068762a32fa9619cc591ceb055b3687f4cd4051ec2e06b"
 dependencies = [
  "proc-macro2",
  "quote",