fix(): image-ref in trivy scan action (#18)

.github/workflows/docker-build.yml

@@ -49,7 +49,7 @@ jobs:
       - name: Run Trivy to check Docker images for vulnerabilities
         uses: aquasecurity/trivy-action@915b19bbe73b92a6cf82a1bc12b087c9a19a5fe2 # v0.28.0
         with:
-          image-ref: "github-to-slack-notifier:${{ env.TIMESTAMP_TAG }}"
+          image-ref: "ghcr.io/${{ github.repository }}/github-to-slack-notifier:${{ env.TIMESTAMP_TAG }}"
           format: 'table'
           exit-code: '1'
           ignore-unfixed: true