chore(deps): bump actions/download-artifact from 4 to 6 (#394)

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 4 to 6.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v4...v6)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/demo-build-and-scan-docker-image.yml

@@ -51,7 +51,7 @@ jobs:
           node-version: '22'
 
       - name: Download SBOM artifact
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: cdxgen-sbom-json
           path: .

.github/workflows/demo-scan-docker-image.yml

@@ -47,7 +47,7 @@ jobs:
           node-version: '22'
 
       - name: Download SBOM artifact
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           name: cdxgen-sbom-json
           path: .