Check for outdated deps in fuzz target

Author: dtolnay

.github/workflows/ci.yml

@@ -112,3 +112,4 @@ jobs:
       - uses: actions/checkout@v3
       - uses: dtolnay/install@cargo-outdated
       - run: cargo outdated --workspace --exit-code 1
+      - run: cargo outdated --manifest-path fuzz/Cargo.toml --exit-code 1