build(deps): bump aquasecurity/trivy-action from 0.19.0 to 0.21.0

Bumps [aquasecurity/trivy-action](https://github.com/aquasecurity/trivy-action) from 0.19.0 to 0.21.0.
- [Release notes](https://github.com/aquasecurity/trivy-action/releases)
- [Commits](aquasecurity/trivy-action@0.19.0...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/nightly.yaml

@@ -111,7 +111,7 @@ jobs:
       # Equivalent to:
       # $ trivy image openpolicyagent/opa:edge-static
       - name: Run Trivy scan on image
-        uses: aquasecurity/trivy-action@0.19.0
+        uses: aquasecurity/trivy-action@0.21.0
         with:
           image-ref: 'openpolicyagent/opa:edge-static'
           format: table
@@ -139,7 +139,7 @@ jobs:
       # Equivalent to:
       # $ trivy fs .
       - name: Run Trivy scan on repo
-        uses: aquasecurity/trivy-action@0.19.0
+        uses: aquasecurity/trivy-action@0.21.0
         with:
           scan-type: fs
           format: table