Test trivy with tar output.

.gitea/workflows/release.yml

@@ -43,6 +43,13 @@ jobs:
         with:
           tags: cs-git.ddnss.de/ri-st/startup:latest
           push: true
+
+      - name: Build and store image for trivy
+        uses: docker/build-push-action@v4
+        env:
+          ACTIONS_RUNTIME_TOKEN: ''
+        with:
+          push: true
           outputs: type=docker,dest=/tmp/startup.tar
 
       - name: Check with trivy