Adding Trivy to scan source code

.github/workflows/security.yml

@@ -0,0 +1,31 @@
+name: Security
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  build:
+    name: Trivy code scanning
+    runs-on: ubuntu-18.04
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Run Trivy vulnerability scanner in repo mode
+        uses: aquasecurity/trivy-action@master
+        with:
+          scan-type: 'fs'
+          ignore-unfixed: true
+          format: 'template'
+          template: '@/contrib/sarif.tpl'
+          output: 'trivy-results.sarif'
+          severity: 'CRITICAL,HIGH'
+
+      - name: Upload Trivy scan results to GitHub Security tab
+        uses: github/codeql-action/upload-sarif@v1
+        with:
+          sarif_file: 'trivy-results.sarif'