Security audit worflow in GitHub

.github/workflows/audit.yml

@@ -0,0 +1,30 @@
+name: Security audit
+on:
+  push:
+    paths:
+      - Cargo.lock
+jobs:
+  security_audit:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - id: ls-crates-io-index
+        name: Get head commit hash of crates.io registry index
+        run: |
+          commit=$(
+            git ls-remote --heads https://github.com/rust-lang/crates.io-index.git master |
+            cut -f 1
+          )
+          echo "::set-output name=head::$commit"
+      - name: Cache cargo registry index
+        uses: actions/cache@v2
+        with:
+          path: ~/.cargo/registry/index
+          key: cargo-index-${{ steps.ls-crates-io-index.outputs.head }}
+          restore-keys: |
+            cargo-index-
+
+      - uses: actions-rs/audit-check@v1
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}