ci: report vulnerabilities and fail on HIGH,CRITICAL (#152)

Add an additional Trivy execution that raises an error on HIGH and CRITICAL vulnerabilities.
It also uploads the vulnerability report to the CI run and the GitHub Security dashboard.

.github/workflows/security.yaml

@@ -1,15 +1,15 @@
 name: Security
 
 on:
-  push:
-    branches: [main]
-  pull_request:
-    branches: [main]
+  schedule:
+    - cron: "0 1 * * *"
 
 jobs:
   scan:
     name: Scan for known vulnerabilities
     runs-on: ubuntu-latest
+    env:
+      TRIVY_RESULTS: 'trivy-results.sarif'
     steps:
       - uses: actions/checkout@v3
 
@@ -18,3 +18,23 @@ jobs:
         with:
           scan-type: 'fs'
           scan-ref: '.'
+          format: 'sarif'
+          output: ${{ env.TRIVY_RESULTS }}
+
+      - name: Upload Trivy scan results to GitHub Security tab
+        uses: github/codeql-action/upload-sarif@v3
+        with:
+          sarif_file: ${{ env.TRIVY_RESULTS }}
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: ${{ env.TRIVY_RESULTS }}
+          path: ${{ env.TRIVY_RESULTS }}
+
+      - name: Raise error on HIGH,CRITICAL vulnerabilities
+        uses: aquasecurity/trivy-action@master
+        with:
+          scan-type: 'fs'
+          scan-ref: '.'
+          severity: 'CRITICAL,HIGH'
+          exit-code: '1'