build: Bump syn from 2.0.60 to 2.0.64 in /fuzz

Bumps [syn](https://github.com/dtolnay/syn) from 2.0.60 to 2.0.64.
- [Release notes](https://github.com/dtolnay/syn/releases)
- [Commits](https://github.com/dtolnay/syn/compare/2.0.60...2.0.64)

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

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

fuzz/Cargo.lock

@@ -806,9 +806,9 @@ checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
 
 [[package]]
 name = "syn"
-version = "2.0.60"
+version = "2.0.64"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "909518bc7b1c9b779f1bbf07f2929d35af9f0f37e47c6e9ef7f9dddc1e1821f3"
+checksum = "7ad3dee41f36859875573074334c200d1add8e4a87bb37113ebd31d926b7b11f"
 dependencies = [
  "proc-macro2",
  "quote",