Audit dependencies

Author: djc

.github/workflows/ci.yml

@@ -83,3 +83,9 @@ jobs:
       - run: cargo install --locked cargo-check-external-types
       - name: run cargo-check-external-types
         run: cargo check-external-types --all-features
+
+  audit:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: EmbarkStudios/cargo-deny-action@v2

deny.toml

@@ -0,0 +1,6 @@
+[advisories]
+yanked = "deny"
+
+[licenses]
+version = 2
+allow = ["Apache-2.0", "MIT"]