Update Docker secrets and container tag in GitHub workflow

In the GitHub workflow for deploying the Docker container, the secrets for Docker username and token have been updated. Also, the tag used for the Docker container is now fetched from a secret, allowing greater flexibility in tagging.

.github/workflows/deploy-container.yaml

@@ -18,12 +18,12 @@ jobs:
       - name: Login to Docker Hub
         uses: docker/login-action@v3
         with:
-          username: ${{ secrets.DOCKERHUB_USERNAME }}
-          password: ${{ secrets.DOCKERHUB_TOKEN }}
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_TOKEN }}
 
       - name: Build and push
         uses: docker/build-push-action@v5
         with:
           context: .
           push: true
-          tags: user/portfolio:latest
+          tags: user/${{ secrets.CONTAINER_TAG }}:latest