added Docker Scout step

.github/workflows/vulnerability-comparison.yaml

@@ -0,0 +1,49 @@
+name: Vulnerability Comparison
+
+on:
+  pull_request:
+    branches: ["**"]
+
+env:
+  # Image repository, without hostname and tag
+  IMAGE_NAME: ${{ github.repository }}
+  SHA: ${{ github.event.pull_request.head.sha || github.event.after }}
+
+jobs:
+  vulnerability-comparison:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ env.SHA }}
+      - name: Set short SHA
+        id: vars
+        run: echo "SHA_SHORT=$(echo $GITHUB_SHA | cut -c1-7)" >> $GITHUB_ENV
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          load: ${{ github.event_name == 'pull_request' }}
+          tags: "ghcr.io/${{ env.IMAGE_NAME }}:${{ env.SHA_SHORT }}"
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+      - name: Authenticate to Docker
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKER_USER }}
+          password: ${{ secrets.DOCKER_PAT }}
+      - name: Docker Scout
+        id: docker-scout
+        uses: docker/scout-action@v1
+        with:
+          command: compare
+          image: "gatewaydio/gatewayd:latest"
+          to: "ghcr.io/${{ env.IMAGE_NAME }}:${{ env.SHA_SHORT }}"
+          ignore-unchanged: true
+          only-severities: critical,high
+          github-token: ${{ secrets.GITHUB_TOKEN }}