CI/CD: Add cargo deny job to GitHub Actions.

.github/workflows/ci.yml

@@ -36,6 +36,24 @@ jobs:
       # TODO: Add `--all-features`:
       - run: cargo +1.37.0 clippy ---all-targets -- --deny warnings
 
+  deny:
+    # Don't run duplicate `push` jobs for the repo owner's PRs.
+    if: github.event_name == 'push' || github.event.pull_request.head.repo.full_name != github.repository
+
+    runs-on: ubuntu-18.04
+
+    steps:
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+
+      - run: cargo install cargo-deny
+
+      - uses: actions/checkout@v2
+
+      - run: cargo deny check
+
   test:
     # Don't run duplicate `push` jobs for the repo owner's PRs.
     if: github.event_name == 'push' || github.event.pull_request.head.repo.full_name != github.repository

deny.toml

@@ -0,0 +1,28 @@
+[advisories]
+unmaintained = "deny"
+yanked = "deny"
+notice = "deny"
+
+[licenses]
+allow = [
+    "Apache-2.0",
+    "ISC",
+    "LicenseRef-ring",
+    "MIT",
+]
+confidence-threshold = 1.0
+
+[[licenses.clarify]]
+name = "ring"
+expression = "LicenseRef-ring"
+license-files = [
+    { path = "LICENSE", hash = 0xbd0eed23 },
+]
+
+[bans]
+multiple-versions = "deny"
+wildcards = "deny"
+
+[sources]
+unknown-registry = "deny"
+unknown-git = "deny"