ci: add audit job

Author: djc

.github/workflows/rust.yml

@@ -87,6 +87,12 @@ jobs:
       - name: Check semver
         uses: obi1kenobi/cargo-semver-checks-action@v2
 
+  audit:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: EmbarkStudios/cargo-deny-action@v2
+
 #  TODO: broken - migrate to criterion
 #  bench:
 #    name: Check that benchmarks compile