build: bump proc-macro2 from 1.0.38 to 1.0.39 in /fuzz

Bumps [proc-macro2](https://github.com/dtolnay/proc-macro2) from 1.0.38 to 1.0.39.
- [Release notes](https://github.com/dtolnay/proc-macro2/releases)
- [Commits](https://github.com/dtolnay/proc-macro2/compare/1.0.38...1.0.39)

---
updated-dependencies:
- dependency-name: proc-macro2
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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

fuzz/Cargo.lock

@@ -518,11 +518,11 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.38"
+version = "1.0.39"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9027b48e9d4c9175fa2218adf3557f91c1137021739951d4932f5f8268ac48aa"
+checksum = "c54b25569025b7fc9651de43004ae593a75ad88543b17178aa5e1b9c4f15f56f"
 dependencies = [
- "unicode-xid",
+ "unicode-ident",
 ]
 
 [[package]]
@@ -713,6 +713,12 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "unicode-ident"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d22af068fba1eb5edcb4aea19d382b2a3deb4c8f9d475c589b6ada9e0fd493ee"
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.3"