Update scan-docker-images-using-trivy.yaml

Author: githubofkrishnadhas

.github/workflows/scan-docker-images-using-trivy.yaml

@@ -29,7 +29,7 @@ jobs:
       env:
         dockerhub_username: 'dockerofkrishnadhas'
       run: |
-          pipenv run python3 get_all_docker_image_tags.py --account_name $dockerhub_username
+          pipenv run python3 get_all_docker_image_tags.py --account_name ${{ env.dockerhub_username }}
     - name: check files
       run: |
         ls -la