ci: add testfuzz workflow

Adds the `testfuzz` workflow to CI for a short fuzz test run on each
pull request.

Author: 0xllx0

.github/workflows/build.yml

@@ -50,6 +50,44 @@ jobs:
       - name: Run miri
         run: MIRIFLAGS=-Zmiri-ignore-leaks cargo miri test --features="alloc,defmt,mpmc_large,portable-atomic-critical-section,serde,ufmt,bytes"
 
+  # Run cargo-fuzz tests on nightly
+  testfuzz:
+    name: testfuzz
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Cache cargo dependencies
+        uses: actions/cache@v3
+        with:
+          path: |
+            - ~/.cargo/bin/
+            - ~/.cargo/registry/index/
+            - ~/.cargo/registry/cache/
+            - ~/.cargo/git/db/
+          key: ${{ runner.OS }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.OS }}-cargo-
+
+      - name: Cache build output dependencies
+        uses: actions/cache@v3
+        with:
+          path: target
+          key: ${{ runner.OS }}-build-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.OS }}-build-
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: nightly
+
+      - name: Run cargo-fuzz test
+        run:
+          - cargo install --locked cargo-fuzz
+          - cargo +nightly fuzz run fuzz_vec -- -runs=16384 -max_len=4096
+
   # Run cargo test
   test:
     name: test