Bump aquasecurity/trivy-action from 0.20.0 to 0.21.0

Bumps [aquasecurity/trivy-action](https://github.com/aquasecurity/trivy-action) from 0.20.0 to 0.21.0.
- [Release notes](https://github.com/aquasecurity/trivy-action/releases)
- [Commits](https://github.com/aquasecurity/trivy-action/compare/0.20.0...0.21.0)

---
updated-dependencies:
- dependency-name: aquasecurity/trivy-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/ci-image-scanning.yaml

@@ -34,7 +34,7 @@ jobs:
           export REGISTRY="docker.io/karmada"
           make image-${{ matrix.target }}
       - name: Run Trivy vulnerability scanner
-        uses: aquasecurity/trivy-action@0.20.0
+        uses: aquasecurity/trivy-action@0.21.0
         with:
           image-ref: 'docker.io/karmada/${{ matrix.target }}:latest'
           format: 'sarif'
@@ -42,7 +42,7 @@ jobs:
           vuln-type: 'os,library'
           output: 'trivy-results.sarif'
       - name: display scan results
-        uses: aquasecurity/trivy-action@0.20.0
+        uses: aquasecurity/trivy-action@0.21.0
         with:
           image-ref: 'docker.io/karmada/${{ matrix.target }}:latest'
           format: 'table'