Re-enable the fuzz check in CI.

Update to cargo-fuzz 0.11, which fixes compatibility with rust nightly.

Author: sunfishcode

.github/workflows/main.yml

@@ -354,15 +354,14 @@ jobs:
   fuzz_targets:
     name: Fuzz Targets
     runs-on: ubuntu-latest
-    if: ${{ false }} # disable pending https://github.com/rust-fuzz/cargo-fuzz/issues/276
     steps:
     - uses: actions/checkout@v2
       with:
         submodules: true
     - uses: ./.github/actions/install-rust
       with:
         toolchain: nightly
-    - run: cargo install cargo-fuzz --vers "^0.8"
+    - run: cargo install cargo-fuzz --vers "^0.11"
     - run: cargo fetch
       working-directory: ./fuzz
     - run: cargo fuzz build --dev