Create audit.yaml (#110)

* Create audit.yaml

* Update audit.yaml

Also run audit on PRs

* Update audit.yaml

set working directory to `sdk`

* Update audit.yaml

set working-directory in with clause?

* Update audit.yaml

invoke cargo-audit manually

Author: rcoh

.github/workflows/audit.yaml

@@ -0,0 +1,22 @@
+name: Security audit
+on:
+  schedule:
+    - cron: '0 0 * * *'
+  workflow_dispatch:
+  pull_request:
+env:
+  rust_version: 1.51.0
+
+jobs:
+  audit:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ env.rust_version }}
+      - name: install cargo audit
+        run: cargo install cargo-audit
+      - name: Run audit
+        working-directory: sdk
+        run: cargo audit